IV Mech Qb Eited

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RANGANATHAN ENGINEERING COLLEGE

Coimbatore- 641 109

DEPARTMENT OF MECHANICAL ENGINEERING

II Year – IV Semester

Batch: 2008

QUESTION BANK

Sl.No Name of the Subject Staff Name Page No

(From – To)

1 Statistics and Numerical

Methods Mrs.Myvizhi 02 – 16

2 Heat and Mass Transfer Prof.P.L.N.Ramesh 17 – 36

3 Manufacturing

Technology – II Mr.K.Marimuthu 37 – 48

4 Engineering Materials &

Metallurgy Mr.P.Senthil Kumar 49 - 60

5 Strength of Materials Mr.A.Sathish Kumar 61 – 73

6 Electronics and

Microprocessor ECE STAFF 74 - 91

STUDENT NAME :

REGISTER NO :

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SUBJECT NAME: STATISTICS AND NUMERICAL METHODS

UNIT I: SOLUTION OF EQUATIONS AND EIGENVALUE PROBLEMS

Part A -2 Mark Questions & Answers

1. Compare Gauss elimination with Gauss Seidal method. Answer: Gauss elimination :(a) Direct Method(b) Used to find inverse of the matrix also.(c) Diagonally dominant condition is not insisted. Gauss Seidal : (a) Indirect (b) Used to solve system of equations only. (c) Diagonally dominant condition is insisted. 2. Write the convergence condition and order of convergence of Newton Rap son method.

Answer: Newton Rap son method convergence condition is

The order of convergence is two. 3. State fixed point theorem and the fixed point iteration formula. Answer: Any function f(x) = 0 is expressed as the fixed point equation x = f(x) whose root is given by the point of intersection of the curves y = x and y = g(x). Fixed point iteration formula:

4. What are the merits of Newton’s method of iteration? Answer: It is applicable to the solution of equations involving algebraically functions as well as transcendental functions. It is successfully used to improve ether result obtained by other methods. 5. Give two indirect methods to solve a system of linear equations. Answer: (a) Gauss Jacobi Method (b) Gauss Seidal Method 6. Under the conditions that f(a) and f(b) have opposite signs and a<b, find the approximation to the root of f(x) = 0 by the method of false position. Answer: If f(x) = 0, has a root in the interval (a, b), the approximate

.

.State the sufficient condition on for the convergence of an iterative method for f(x) = 0 written as x

= )

Answer: Sufficient condition for convergence of an iterative method let f(x) = 0 written as x = f(x). If ) is a

continuous function on some interval [a, b] that contains the root and in this interval, them for

any choice of the sequence from converges to the root of the functions. 8. State the condition for the convergence of Gauss Seidal iterative method for solving system of equations.

Answer: >

>

>

9. Why Gauss Seidal iteration is a method of successive corrections? Answer: Because we replace approximations by corresponding new ones as soon the latter have been computed. 10. State the criterion for the converges in Newton Rap son method?

Answer: Newton Rap son method converges if in the interval considered.

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11. Find the first approximation to the root lying between 0 and 1 of by Newton‟s method.

Answer: f(x)=

and let = 0

=

12. What is the order of convergence of fixed point iteration x = g(x) method? Answer: The order of convergence of convergence of x = g(x) method is one.

13. What is the sufficient condition for the convergence of x= method?

Answer: The sufficient condition for the convergence is for all x in the interval I containing the root x=

of the equation f(x)=0, which can be written as x = .

14. How do you express for the positive root by iteration method?

Answer: Given , therefore,

15. State the principle involved in Gauss elimination method of solving a system of equations. Answer: Augmented matrix (A,B) reduced in to (U,K) and solution is obtained from the equivalent upper triangular system of equation by back substitution. 16. Solve 3x+2y=4; 3x-3y=7 by Gauss Elimination method.

Answer:

Therefore, 3x+2y=4 and . Hence, y=-1 and x=2.

17. Solve by Gauss elimination method, 2x+y=4, x+2y =5

Answer:

That is x+2y =5 and -3Y=-6 therefore, x=1 and y=2. 18. Distinguish between direct and indirect method of solving a system of equations Ax=B. Answer: Direct methods involve a certain amount of fixed computation. But in indirect methods the solution is obtained by successive approximations and the amount of computation depends on the degree of required accuracy. PART B

1. (a). Find the positive root of = 0 by the Regula Falsi method. (b). Find an approximate root of xlog10x - 1.2 = 0 by Regula Falsi method.

2. (a). Solve the equation = 2 by Regula Falsi method.

(b). Find to 4 decimals by Newton‟s Method, a root – 4.

3. (a). Find the iteration formula to find where N is a positive integer by Newton‟s method and hence find

(b) Derive a Newton-Rap son iteration formula for finding the cube root of positive number N. Hence find

4. (a). Obtain an iteration formula, using N - R values to find the reciprocal of a given number N and hence find ,

correction of 4 decimal places.

(b). Find the double root of choosing with the initial value of 0.8.

5. (a). Find a real root of the equation (b). Find a real root of the equation cos x = 3x-1 correct to 5 decimal places fixed point iteration method.

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6. Solve the following system of equation using Gauss – elimination method 2x + y + 4z = 12, 8x -3y +2z = 20, 4x +11y – z =33.

7. (a) Using Gauss-Jordan method, solve the following system of equations 3x+4y-7z =23, 7x-y+2z = -14, x+10y-2z = 33. (b) Using Gauss-Jordan method, solve the following system of equations 2x –y +2z = 8, -x +2y + z = 4, 3x + y -4z = 0 8. (a) Find the numerically largest Eigen values of

1 3 0 2 0 -4

by power method corresponding Eigen vector (correct to 3 decimal places). Start with initial Eigen value

(b) Determine the largest Eigen value and the corresponding Eigen vector correct to 3 decimal places, using power method for the matrix

-1 2 -1 0 -1 2 UNIT II: INTERPOLATION AND APPROXIMATION


1. Define the terms interpolation and extrapolation. Answer: Interpolation is the technique of estimating the value of a function for any intermediate value at the independent variable while the process of computing the value of the function outside the given range is called extrapolation. 2. Show that the divided differences are symmetrical in their arguments.

Answer:

3. Obtain a divided difference table for the following data. X 5 7 11 13 17 Y 150 392 1452 2366 5202 Answer:

X Y

5

7

11

15 0

39 2

14 52

12 1

26 5

24

32

1

5

13

17

23 66

5202

45 7

70 9

42

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4. Explain the use of Lagrange’s interpolation formula for inverse interpolation? Answer: Lagrange‟s interpolation formula is a relation between two variables x and y which either x or y is taken as independent variable. Replacing x by y and y by x in Lagrange‟s formula. We can use the resulting formula for finding x for a given y. 5. State any two properties of divided differences. Answer: i) The divided differences are symmetrical in all their arguments. ii) The divided differences of sum or difference of two functions is equal to the sum or difference of the corresponding separate divided difference. 6. State Newton’s divided difference interpolation formula. Answer:

7. What is cubic spline? Answer: A Cubic polynomial which has continuous slope and curvature is called a cubic spline. 8. What is natural cubic spline? Answer: A cubic spline fitted to the given data such that the end cubic approach linearly at their extremities is called a natural cubic spline. 9. State the conditions required for a natural cubic spline. Answer: A cubic spline g(x) fits to each of the points is continuous and is continuous in slope and curvature such that

is called a natural cubic spline.

10. Write the divided difference table given X : 1 2 4 7 Y : 22 30 82 106 Answer: f(1,2) =8,f(2,4) =26,f(4,7)=8; F(1,2,4)=6,f(2,4,7)=-3.6 and f(1,2,4,7)=-1.6. 11. State Newton-Gregory forward difference interpolation formula.

Answer: = p where p =

12. When will we use Newton’s forward interpolation formula? Answer: Newton‟s forward interpolation formula is used when interpolation is required near the beginning of the table

value and for extrapolation at a short distance from the initial value .

13. State Newton’s backward interpolation formula.

Answer: = where p =

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14. Starting with x=2,y=1, find the values of x and y after one iteration while solving 5x+2y=19 and 3x+7y=23 by Gauss – Seidal method.

Answer:

15. Find the inverse of by Gauss Jordan method.

Answer: (A/I) =

Therefore

PART B 1. (a) Find the Lagrange‟s polynomial of degree 3 to fit the data y(0)= - 12, y(1)=0,y(3)=6 and y(4) =12. Hence

find y(2). (b) Using Lagrange‟s formula fit a polynomial to the data X: -1 0 2 3 Y: -8 3 1 12 Hence find y at x=1.5 and x=1 2. (a). Using Lagrange‟s formula fit a polynomial to the data X: 0 1 2 4 5 6 F(x): 1 14 15 5 6 19 Also find f(3). (b). Using Lagrange‟s formula, find y at x=6 for the following data: X: 2 5 7 10 12 Y: 18 180 448 1210 2028 3. (a). Find the age corresponding to the annuity value 13.6 given the table

Age (x) 30 35 40 45 50 Annuity value (y) 15.9 14.9 14.1 13.3 12.5 (b). If f(0) = 0 , f(1) = 0, f(2) = -12, f(4) =(0), f(5) =600 and f(7) = 7308,find a polynomial that satisfies this data

using Newton‟s divided difference interpolation formula. Hence, find f(6) 4. (a). Using Newton‟s divided difference formula find f(x) and f(6) from the Following data: X: 1 2 7 8 f(x) 1 5 5 4 (b). Using Newton‟s divided difference formula find the value of f(8) and f(6) from the following data: X: 4 5 7 10 11 13 f(x) 48 100 294 900 1210 2028 5. (a). Given the following table, find f(2.5) using cubic spline functions: I: 0 1 2 3 Xi: 2 3 12 147 f(Xi): 0.5 0.3333 0.25 0.2 (b). The following values of X and Y are given: X: 1 2 3 4 Y: 1 2 5 11 Find the cubic spline and evaluate Y (1.5).

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6. (a). Find the cubic spline for the data: X: 0 1 2 3 f(x): 1 2 9 28 (b). From the following table X: 1 2 3 f(x): -8 -1 18 Compute y(1.5) and y1(1), using cubic spline 7. (a). Find the polynomial of degree two for the data by Newton‟s forward difference method: X: 0 1 2 3 4 5 6 7 F(x) 1 2 4 7 11 16 22 29 (b). From the following table of half-yearly premium for policies maturing at different ages, estimate the premium

for policies maturing at age 46 and 63 Age X: 45 50 55 60 65 Premium: 114.84 96.16 83.32 74.48 68.48

UNIT III: NUMERICAL DIFFERENTIATION AND INTEGRATION


1. State Newton’s forward difference formula to find at .

Answer:

2. Write the formula to compute at for a given data (x,y).

Answer:

3. Write the formula to compute at for a given data (x,y)

Answer: where p=

4. Find at x=2 from the following

X: 2 3 4 Y: 26 58 112 Answer:

x Y

2

26

32

8

3

4

58

11 2

54

22

5. Find at x=6 from the following data

X: 2 4 6 Y: 3 11 27

Answer:

x y

2

4

6

3

11

27

8

16

8

6. What is the order of the error in trapezoidal rule?

Answer: The error in the trapezoidal rule is of the order 7. Why is trapezoidal rule so called? Answer: Because trapezoidal rule approximates the integral by the sum of n trapezoidal. 8. In numerical integration, what should be the number of intervals to apply Simpson’s one third rule and Simpson’s three eights rule?

Answer: For Simpson‟s one-third rule, the number of intervals must be even. For, Simpson‟s Rule, the number of

Intervals in a multiple of 3.

9. State the basic principle for deriving Simpson’s rule.

Answer: The curve passing through three consecutive points is replaced by a parabola. 10. A curve passes through (2,8),(3,27),(4,64) and (5,125). Find the area of the curve between x-axis and the lines x=2 and x=5 by Trapezoidal rule. Answer: X : 2 3 4 5

: 8 27 64 125

= sq.units.

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11. Evaluate by Trapezoidal rule with h=0.5

Answer: X : 0 0.5 1 Y : 1 0.8 0.5

=

12. If =0.7828, Find using Romberg’s method.

Answer: By Romberg‟s method

13. Find by two point Gaussian formulas.

Answer: =1.5

PART– B

1. (a). Find the value of f ‟(8) from the following table x : 6 7 9 12 f(x) : 1.556 1.690 1.908 2.158 (b). Given that x : 1.1 1.2 1.3 1.4 1.5 y : 8.403 8.781 9.129 9.451 9.75

find and y at x=1.1.

2. (a). Find at x = 1.5 given

x : 1 2 3 4 5 y : 77 78 127 248 375 (b). Find the first and second derivatives of y w. r. to x at x = 10 x : 3 5 7 9 11 y : 31 43 57 41 27

3. (a). Find and at x=10 for the following data

x: 2 4 6 8 10 y: 6 54 134 246 390 (b). Find the maximum and minimum value of y = f(x) given the data x : 0 1 2 3 4 5 f(x) : 0 1/4 0 9/4 16 225/4 4. (a). A river is 80 mts wide. The depth‟s‟ in mts at a distance x mts from one bank is given by the following table.

Calculate the area of cross section of the river using Simpson‟s 1/3 rd rule X: 0 10 20 30 40 50 60 70 80 D: 0 4 7 9 12 15 14 8 3

(b). By dividing the range into equal parts, evaluate by using Simpson‟s 1/3 rd rule

5. (a). Evaluate by Trapezoidal rule and Simpson‟s 3/8 rule.

(b). Calculate taking 5 ordinates by trapezoidal rule and Simpson‟s 1/3 rule.

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6. (a). Evaluate by using Simpson‟s 1/3rd rule taking ∆x = ∆y = 0.25

(b). Evaluate taking h = k = 0.5 by both trapezoidal rule and Simpson‟s

Rule.

7. Evaluate using h=k=0.5 using Simpson‟s 1/3 rule in x direction

And Trapezoidal rule in the y direction.

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UNIT IV INITIAL VALUE PROBLEMS FOR ORDINARY DIFFERENTIAL EQUATIONS


1. What are the merits and demerits of the Taylor series of solution?

Answer: It is a powerful single step method. It is the best method if the expression for higher order derivatives is simpler.

The major demerit of this method is the evaluation of higher order derivates become tedious for complicated algebraic

expressions.

2. Find y(0.1) from by Euler’s method.

Answer:

That is y (0.1) =1.10

3. Given Find y(0.01),y(0.02) by Euler’s method.

Answer:

That is (0.01) =0.99

That is y (0.02) =0.9801

4. State Runge-Kutta forth order formulae for solving

Answer: where

5. What are the distinguished properties of Runge-Kutta methods?

Answer:

(i) These methods do not require the higher order derivatives and requires only the function values at different

points.

(ii) To evaluate , we need only but not previous of y‟s.

(iii) The solution by these methods agrees with Taylor‟s series solution up to the terms of where r is the order of

the Runge-Kutta method.

6. Which is better Taylor series method or Runge-Kutta method? why?

Answer: Runge-Kutta method is better since higher order derivatives of y are not required. Taylor series method

involves use of higher order derivatives which may be difficult in case of complicated algebraic functions.

7. State the order of error in R-K method of fourth order.

Answer: Error in R-K fourth order method is where h is the interval of diffdrencing.

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8. State Milne’s predictor corrector formula.

Answer: Predictor:

Corrector:

9. Write Adam’s predictor corrector formula.

Answer: Predictor:

Corrector: +

10. Write down the modified Euler’s formula for ODE.

Answer:

11. Give a comparison of Adam’s Bash forth method with R.K.Method

Answer:

1. AB‟s method required four starting values of y. Hence, it is referred as a multi-step method. R.K.methods are single

step method.

2. R.K.method is self starting as it does not require more than the initial value of y, where as the PC methods are not

self starting as values of y at prior points are used.

12. Explain one step methods and multistep methods.

Answer: In one step methods, in each step, we use the data of just one proceeding step. In multi step methods where

in each step, we use data from more than one of the proceeding steps.

13. Mention the multi-step methods available for solving ODE.

Answer:

(i) Milne‟s predictor corrector formula

(ii) Adam‟s predictor corrector formula.

1 4. What do mean by saying that a method is self starting? Not self starting?

Answer: Iteration method is self starting since we can take value which lies in the given interval [a,b] in which the root lies.

But Milne‟s method is not self starting. Since we should know any 4 values prior to the value which we need.

15. What do you mean by error in error analysis?

Answer: Numerical errors arise from the use of approximations to represent exact mathematical operations and quantities

True Value = approximation + errors

PART – B

1. (a). Using Taylor series method find y at x = 0.1 if ,y(0)=1.

(b). Solve , y(0)=1. Use Taylor series at x=0.2 and 0.4, Find x = 0.1.

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2. (a).Solve the system of equations with y(0) = 1, z(0) = 1 by taking h = 0.1 , to get y(0.1)

and z(0.1).Here y and z are dependent variables and x is independent.

(b). Using Taylor series method, find y(1.1) and y(1.2) correct to four Decimal places given and y(1) =1.

3. (a).By Taylor‟s series method find y(0.1) given that y‟‟ = y + xy‟ , y(0) =1 , y‟(0) = 0 .

(b). Using Euler‟s modified method find y(0.1) from y'x y xy, y(0) 1, with h=0.05.

4. (a). Using Euler‟s method find y(0.3)of y(x) satisfies the initial value problem.

y(0.2)=1.1114, with h=0.1

(b). Using modified Euler‟s method, compute y(0.1) with h=0.1 from , y(0)=1.

5. (a). Solve y'1-y, y(0) 0, find y(0.1) by modified Euler‟s method.

(b). Given ,y(0)=2. Compute y(0.2), y(0.4) and y(0.6) by Runge-Kutta method of fourth order.

6. (a). Using R.K. method of 4th order, solve y (0) =1 at x = 0.2.

(b). Using R.K. method of fourth order find y(0.1) for the initial value problem

,y(0)=1.,take h=0.1

7. Determine the value of y(0.4) using Milne‟s method Given ,y(0)=1use Taylor series to get the values of

y(0.1), y(0.2) and y(0.3).

8. Given y‟ = 1-y and y (0) = 0, find

(i) y (0.1) by Euler method

(ii)y (0.2) and y(0.3) by modified Euler method

(iii)y (0.4) by Milne‟s method

9. (a). Using Milne‟s method find y(4.4) given 5 xy’ y given y(4)=1, y (4.1) =1.0049,y(4.2)=1.0097 and y(4.3) = 1.0143.

(b).Given , y(1)=1,y(1.1)=1.233,y(1.2)=1.548, y (1.3)=1.979 evaluate y(1.4) by Adams – Bash forth

method.

10. Consider the initial value problem ,y(0)=0.5

(a). using Taylor series , find y(0.2)

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(b). Using 4th order Runge-Kutta method, find y(0.4) and y(0.6)

(c). Using Adam-Bash forth Predictor- Corrector method. Find y(0.8).

UNIT V BOUNDARY VALUE PROBLEMS IN ORDINARY AND PARTIAL DIFFERENTIAL EQUATIONS


1. Derive the forward finite difference formula .

Answer: Keeping y fixed, using Taylor‟s series

2. Obtain the finite difference scheme for solving Laplace equation.

Answer:

3. In the parabolic equations if where k = and h = , then for what value , explicit method

instable and implicit method is convergent?

Answer: Explicit method is stable only if < ½ and implicitly method is convergent if < ½.

4. Name at least twp numerical methods that are used to solve one dimensional diffusion equation.

Answer: (i) Bender-Schmidt method. (ii) Crank-Nicholson method

5. Define difference quotient of a function y(x).

Answer: A difference quotient is the quotient obtained by dividing the difference between two values of a function by the difference between two corresponding values of the independent variable.

6. What is te error for solving Laplace and Poisson’s equations by finite difference method.

Answer: The error in replacing by the difference expression is the order

Since, h=k, the error in replacing by the difference expression is of the order .

Hence, the error for solving Laplace and Poisson .

7. Write down the Bender-Schmidt recurrence for one dimensional heat equation.

Answer: The Bender-Schmidt recurrence relation for one dimensional heat equation is

8. What is the purpose of Leibmann’s process?

Answer: The purpose of Leibmann‟s process is to find the solution of Lalplace equation by iteration over a

square with boundary values.

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9. In the explicit formula for solving one dimensional equation = , what is the simplest form to explicit

scheme?

Answer:

10. What are piece wise polynomials?

Answer: An interpolation polynomial of degree n can be constructed from a given set of n+1 values of the function. But it produces incorrect estimates of the function sometimes. To overcome this problem, the given range of points is divided into sub intervals and in each sub interval, a low – order polynomial is used for interpolation. Such polynomials are called piecewise polynomials.

11. What are Spline functions?

Answer: The piecewise polynomials constructed in every sub interval of the given range which prevents discontinuity or the interpolating points or connecting points are called spline functions.

12. What is Spline interpolation polynomial?

Answer: Each interval of the given range wil have a different polynomial of degree m or less. The set of all polynomials form a spline interpolation polynomial is the set os tabulated values of y=f(x).

13. What are Cubic Splines?

Answer: Cubic splines are piece wise cubic interpolating polynomials and these are smooth curves to interpolate data.

PART – B

1. (a). Solve by finite difference method, the boundary value problem y‟‟(x) – y(x) = 2 where y(0) = 0 and y(1) = 1, taking h = ¼ .

(b).Using the finite difference method, find y(0.25), y(0.5) and y(0.75) satisfying the differential equation y‟‟(x) + y = x

Subject to the boundary condition y(0) = 0 , y(1) = 2.

2.Solve given u(0,t)=0, u(4,t)=0,u(x,0)=x(4-x) taking x= t=1. Find the value of u up to t=3 using Bender-Schmidt explicit difference scheme

3. Solve the Laplace‟s equation over the square mesh of side 4 units satisfying the boundary conditions:

U(0,y)=0,0 y 4 ;u(4,y)=12+y, 0 y 4

U(x,0)=3x, 0 x 4 ;u(x,4)= ,0x 4

4. By iteration method, solve the lap lace equation uxx+ uyy =0 , over the square region ,satisfying the boundary condition .

u(0, y) = 0 , 0< y< 3

u(3, y) = 9+y , 0< y< 3

u(x,0) = 3x , 0< x< 3

u(x, 3) = 4x , 0<x< 3

5. Solve uxx+uyy = 0 for the following square mesh with boundary values as shown in the figure below

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6. Solve over the square mesh with sides x=0,y=0,x=3,y=3 with u=0 on the boundary

and mesh length of 1 unit.

7. Solve the Poisson equation over the square region bounded by the

over the square region bounded by the lines x=0, y=3 given that u=10 throughout the

boundaries taking h=1.

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SUBJECT NAME: HEAT & MASS TRANSFER

UNIT – I CONDUCTION


1. What is Fourier's Law of heat conduction?

Q=-KA dT/dx

2. What is temperature gradient?

dT/dx

3. What is coefficient of Thermal conductivity?

Heat conducting capacity of a material

4. Give some examples of heat transfer in engineering.

I.C. engines, Gas Turbines, Jet Propulsion, air conditioning systems

5. Define heat flux.

Rate of heat transfer per unit area ( q) W/m2

6. Define thermal Diffusivity.

It depicts how fast the heat is diffuses through the material during the changes of temperature with time. α=k/ρcp

7. What is Laplace equation for heat flow?

▼2.T = 0

8. What is Poisson's equation for heat flow?

▼2.T+q/k = 0

10. What critical radius of insulation?

Rc= k/h

11. What is a Fin?

An extended surface to augument ( increase)rate of heat transfer through the surface

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12. Define efficiency of the fin.

Efficiency of a fin =Qfin/Qmax

13. Define effectiveness of the fin.

Effectiveness of a fin= Q with fin/Q without fin

14. Give examples of use of fins in various engineering applications.

IC Engines, Air Compressors, Condensers, Evaporators

15. What is meant by Transient heat conduction?

Heat transfer rate is dependent on time

16. Give governing differential equation for the one dimensional transient heat flow.

▼2.T = 0=1/α. dT/dι

18. What is Biot number?

Bi= Internal resistance / Convective resistance = hL/K

19. What is Newtonian heating or cooling process?

If internal resistance is negligible in comparison with surface resistance

20. Give examples for Transient heat transfer.

Cooling of I.C.engines, Electrc irons, cooling of food,heating and cooling of buildings

21. What is meant by thermal resistance?

R=(T1-T2)/K

22. What is meant by periodic heat transfer?

Temperature of the object varies on a periodic basis . Eg. Heating and cooling of earth

23. What are Heisler chart?

Plot for Temperature distribution vs Fourier Number depicting the values of 1/Biot Number.

24. What is the function of insulating materials?

To prevent heat loss from the thermal device/ equipment.

25.What are the conditions to be satisfied for the application of a thermal circuit ?

The problem must be a steady state, one-dimensional heat transfer problem.

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26.Will the thermal resistance of a rectangular slab be increased or decreased if:

a. the thermal conductivity is increased ? b. the cross sectional area is increased ? c. the thickness of the slab is increased ?

a. resistance will decrease b. resistance will decrease c. resistance will increase

28.State the condition which must be satisfied to treat the temperature distribution in a fin as one-dimensional.

When ht/k <<1 where h is the convective heat transfer coefficient, t is the thickness of the fin and k is the thermal conductivity of the fin, one can consider that the temperature gradient in the thickness direction is very small and the analysis can be considered as one-dimensional.

29.Define and state the physical interpretation of the Biot number.

The Biot number is given by: Bi = hL/k where h = convective heat transfer coefficient,

k = thermal conductivity L = characteristic length.

It is a ratio of the temperature drop in the solid material and the temperature dropthe solid and the fluid. So when the Bi <<1 , most of the temperature drop is in the fluid and the solid may be considered isothermal

30.What is a lumped system ?

A lumped system is one in which the dependence of temperature on position (spatial dependence) is disregarded. That is, temperature is modeled as a function of time only .

31.When can the unsteady temperature in a spatial body be considered uniform ?

When the Biot number is small (Bi << 0.1).

32.What is the Fourier number ?

The Fourier number is defined as: Fo = α t/L2

Where

α = thermal diffusivity, t = time L = characterisitic length

The Fourier number is a dimensionless measure of time used in transient conduction problems.

33. What is internal energy generation ? Give examples where internal energy generation occurs

Internal energy generation is the generation of heat within a body by a chemical, electrical or nuclear process.

Examples are the heating of a nuclear fuel rod (due to fission within the rod), the heating of electrical wires (due to the

conversion of electrical to heat energy), microwave heating and the generation of heat within the Earth. The heat

generated in each case is being converted from some other form of energy.

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34. What do you understand by stability criterion for the solution of transient problems ?

When solving transient problems using finite-difference methods, it is possible that the solution undergoes numerically induced oscillations and becomes unstable i.e. the temperature values diverge. The stability criterion is a restriction on the values of Dt and Dx which ensures that the solution remains stable and converges. The criterion is usually expressed as a function of Fourier's number. For example, for an interior node in a two dimensional system the stability criterion is : Fo < 1/4 or aDt/(Dx)

2 < 1/4

35. Both the Nusselt number and the Biot number have the same form. What are the differences between them in

terms of the variables employed and their physical significance ?

Both the Biot number and the Nusselt number are of the form (hL/k). However, for the Biot number, the thermal conductivity k used is that for the solid; for calculating Nusselt number the k value as that of the fluid. The Biot number is a measure of the ratio of the temnperature drop in the solid material and the temperature drop between the solid and the fluid. The Nusselt number is a dimensionless version of the temperature gradient at the surface between the fluid and the solid, and it thus provides a measure of the convection occurring from the surface.

36. What is the effect of the Prandtl number of a fluid on the relative thicknesses of velocity and temperature

boundary layers when the fluid flow is parallel to a flat plate ?

For laminar flow, the ratio of the boundary layer thickness d to that of the thermal boundary layer, dt, is given by: d/dt µ Pr

n The higher the Prandtl number, the larger is the ratio.

PART – B

01. A pipe consists of 100 mm internal diameter and 8 mm thickness carries steam at 170°C. The convective heat transfer

coefficient on the inner surface of pipe is 75 W/m2C. The pipe is insulated by two layers of insulation. The first layer of

insulation is 46 mm in thickness having thermal conductivity of 0.14 W/m°C. The second layer of insulation is also 46

mm in thickness having thermal conductivity of 0.46 W/mC. Ambient air temperature = 33°C. The convective heat

transfer coefficient from the outer surface of pipe = 12 W/m2C. Thermal conductivity of steam pipe = 46 W/m°C.

Calculate the heat loss per unit length of pipe and determine the interface temperatures. Suggest the materials used

for insulation.

02. A long rod is exposed to air at 298°C. It is heated at one end. At steady state conditions, the temperature at two points

along the rod separated by 120 mm are found to be 130°C and 110°C respectively. The diameter of the rod

is25mmOD and its thermal conductivity is 116 W/m°C. Calculate the heat transfer coefficient at the surface of the rod

and also the heat transfer rate.

03. (i) A furnace wall consists of three layers. The inner layer of 10 cm thickness is made of firebrick (k =1.04 W/mK). The

intermediate layer of 25 cm thickness is made of masonry brick (k = 0.69 W/mK) followed by a 5 cm thick concrete wall

(k = 1.37 W/mK). When the furnace is in continuous operation the inner surface of the furnace is at 800°C while the

outer concrete surface is at 50°C. Calculate the rate of heat loss per unit area of the wall, the temperature at the

interface of the firebrick and masonry brick and the temperature at the interface of the masonry brick and concrete.

(ii) An electrical wire of 10 m length and 1 mm diameter dissipates 200 W in air at 25°C. The convection heat transfer

coefficient between the wire surface and air is 15 W/m2K. Calculate the critical radius of insulation and also determine

the temperature of the wire if it is insulated to the critical thickness of insulation.

04. (i) An aluminum rod (k =204 W/mK) 2 cm in diameter and 20 cm long protrudes from a wall which is maintained at

300°C. The end of the rod is insulated and the surface of the rod is exposed to air at 30°C. The heat transfer coefficient

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between the rod's surface and air is 10 Vl/m2K. Calculate the heat lost by the rod and the temperature of the rod at a

distance of 10 cm from the wall.

(ii) A large iron plate of 10 cm thickness and originally at 800°C is suddenly exposed to an environment at O°C where the

convection coefficient is 50 W/m2K. Calculate the temperature at a depth of 4 cm from one of the faces 100 seconds

after the plate is exposed to the environment. How much energy has been lost per unit area of the plate during this

time

05. (i) ) Explain the different modes of heat transfer with appropriate expressions.

(ii) A composite wall consists. of 10 cm thick layer of building brick, k = 0.7 W/mK and 3 cm thick plaster, k = 0.5 W/mK.

An insulating material of k = 0.08 W/mK is to be added to reduce the heat transfer through the wall by 40%. Find its

thickness.

06. Circumferential aluminum fins of rectangular profile (1.5cmwide and 1mm thick) are fitted on to a 90 mm engine

cylinder with a pitch of 10 mm. The height of the cylinder is 120 mm. The cylinder base temperature before and after

fitting the fins are 200°C and 150°C respectively. Take ambient at 30°C and h(average) =100 W/m2K.Estimate the

heat dissipated from the finned and the unfinned surface areas of cylinder body.

07. (i) Derive the heat conduction equation in cylindrical co-ordinates using an elemental volume for a stationary isotropic

solid.

(ii) A 3 cm OD steam pipe is to be covered with two layers of insulation each having a thickness of 2.5 cm. The

average thermal conductivity of one insulation is 5 times that of the other. Determine the percentage decrease in heat

transfer if better insulating material is next to pipe than it is the outer layer. Assume that the outside and inside

temperatures of composite insulation are fixed.

08. (i) Explain briefly the concept of critical thickness of insulation and state any two applications of the same.

(ii) A 6 em long copper rod (k = 300 W/mK) 6mm in diameter is exposed to an environment at 20°C. The base

temperature of the rod is maintained at 160°C. The heat transfer co-efficient is 20 W/m2K. Calculate the heat given by

the rod and efficiency and effectiveness of the rod.

09. (i) Define the Biot and Fourier numbers.

(ii) What is meant lumped capacity? What are the physical assumptions necessary for a lumped capacity unsteady

state analysis to apply?

(iii)A slab of Aluminum 5 cm thick initially at 200°C is suddenly immersed in a liquid at 70°C for which the convection

heat transfer co-efficient is 525 W/m2K. Determine the temperature at a depth of 12.5 mm from one of the faces 1

minute after the immersion. Also calculate the energy removed per unit area from the plate during 1 minute of

immersion. Take P = 2700 bar, Cp = 0.9 kJlkg. OK, k=215W/mK, ά = 8.4X 10-5 m2/s.

10. A composite wall is formed of a 2.5 cm copper plate (k = 355 W/m.K), a 3.2 mm layer of asbestos (k = 0.110 W/m.K)

and a 5 cm layer of fiber plate (k = 0.049 W/m.K). The wall is subjected to an overall temperature difference of 560°C

(560°C on the Cu plate side and O°C on the fiber plate side). Estimate the heat flux through this composite ~all and the

interface temperature between asbestos and fiber plate.

11. A steel tube k=43.26 W/mK of 5.08 cm 10 and 7.62 cm 00 is covered with 2.54 cm of asbestos Insulation k=0.208

W/mK The inside surface of the tube receives heat by convection from a hot gas at a -temperature of 316°C with heat

transfer coefficient ha=284 W/m2K while the outer surface of Insulation is exposed to atmosphere air at 38°C with heat

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transfer coefficient of 17 W/m2K Calculate heat loss to atmosphere for 3 m length of the tube and temperature drop

across each layer.

12. (i) A plane wall 20 cm thickness generates heat at the rate of 5 x 104 W/m3 when an electric current is passed through

it. The convective heat transfer coefficient between each face of the wall and the ambient air is 60 W/m2K. Determine.

(i) The surface temperature

(ii) The maximum temperature in the wall. Assume ambient air temperature to be 25°C and the thermal

conductivity of the wall material to be 16 W/mK.

(ii) A steel ball 100 mm diameter was initially at 50~C and is placed in air which is at35°C. Calculate time required to

attain 400°C and 300°C. k steel = 35 W/mK c = 0.46 kJI kgK, ρ= 7800 kg/m3 h = 10 W/m

2K

UNIT – II CONVECTION


1. What is Convective heat transfer?

The movement of the fluid is due entirely to density gradients within the fluid due to either internal factors or internal

factors.

2. Sketch formation of boundary layer and show laminar, transition & turbulent flow.

3. Write down differential equation for Continuity of fluid flow.

4. State Newton's law of cooling.

Q= h A (t2-t1)

5. Differentiate between Natural & Forced convection.

In natural convection, the movement of the fluid is due entirely to density gradients within the fluid (e.g. hot air rises over cold air). There is no external device or phenomenon which causes fluid motion. In forced convection, the fluid is forced to flow by an external factor - e.g. wind in the atmosphere, a fan blowing air, water being pumped through a pipe. Typically heat transfer under forced convection conditions is higher than natural convection for the same fluid.

6. State Buckingham's Π theorem.

The number of independent dimensionless groups that can be formed from a set of „n‟ variables having „r‟ basic

dimensions is (n-r).

7. What is meant by Dimensional analysis?

Method by which information about a phenomenon from the single premise that the phenomenon can be described by

a dimensionally correct equation among certain variables.

8. Sketch boundary layer development in a circular pipe.

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9. What is Reynolds analogy?

Stx.=Cfx/2

10. What is Colburn analogy?

Stx.Pr2/3

=Cfx/2

11. Define the Bulk temperature.

Total energy of the flow at the particular location.

12. Define velocity boundary layer thickness.

The thickness of the boundary layer has been arbitrarily defined as the distance from the surface at which the local

velocity reaches 99% of the external velocity.

13. Define thermal boundary layer thickness.

The thickness of the boundary layer has been arbitrarily defined as the distance from the surface at which the local

temperature reaches 99% of the external temperature.

14. Distinguish between laminar & turbulent flow.

Laminar: Fluid motion is highly ordered whereas motion in the turbulent boundary layer is highly irregular with the fluid

moving to and from in all directions.

15. What is meant by critical Reynolds number?

Critical distance beyond which the flow can‟t retain its laminar character is usually specified in Critical Reynold‟s

number.

16. Define skin friction coefficient.

Cf = τ/0.5ρU2

17. Give examples for free convection.

Refrigerating coilshot radiators,transmission lines, heat transfer from pipes

18. Define Grassof number.

Ratio of Buoyancy force to the Viscous force

19. Sketch, temperature and velocity profiles in free convection on a vertical wall.

20. List the dimensionless numbers.

Prandtl Number, Biot Number, fourier Number, Reynolds Number

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21. What are the uses of dimensional analysis?

To reduce the number of independent variables in a a problem. Combine the variables of the problem into groups.

22 What are the limitations of Dimensional analysis?

Doesn‟t give the precise relationship among the non-dimensional groups.

23. Two fluids, with different properties, flow with equal free stream velocities parallel to a flat plate. What property of the fluid determines whether the velocity boundary layer of one is thicker than the other ?

The thickness of the boundary layer depends on the Reynolds number:

24. What do you understand by the terms fully developed velocity and temperature profile regions in internal flow

In the fully developed region, the cross-sectional velocity/temperature profile is of a constant shape at any axial location. Thus the profile has ceased to change. Also there is no radial component of velocity i.e. every particle of fluid is flowing purely in the axial direction.

25. Do you expect the convective heat transfer coefficient in the thermally developing region to be higher or lower than the convective heat transfer coefficient in the fully developed temperature profile region ? Support your answer with qualitative logic.

We should expect that the convective heat transfer coefficient is higher in the thermally developing region. Near the tube entrance, the thickness of the boundary layer is very small, and the temperature gradients at the surface will be high, implying high rates of convective heat transfer. As the flow develops, the thickness of the boundary layer increases and the temperature gradients decreases, decreasing h. In the fully developed region, the temperature gradients are constant and h is also a constant.

26. Explain why the temperature boundary layer grows much more rapidly than the velocity boundary layer in liquid metals.

Liquid metals are characterised by very low Prandtl numbers since their thermal conductivity is high, hence the heat diffusion is much faster than momentum diffusion.

27. You are told that in a particulat case of fluid flow over a flat plate the temperature boundary layer thickness is much smaller than the velocity boundary layer thickness. What can you conclude about the nature of the fluid ?

You can conclude that the fluid is a high Prandtl number fluid e.g.oil.

28. How is natural convection different from forced convection?

In natural convection, the movement of the fluid is due entirely to density gradients within the fluid (e.g. hot air rises over cold air). There is no external device or phenomenon which causes fluid motion. In forced convection, the fluid is forced to flow by an external factor - e.g. wind in the atmosphere, a fan blowing air, water being pumped through a pipe. Typically heat transfer under forced convection conditions is higher than natural convection for the same fluid.

PART – B

01. Air at 200 kPa and 200°C is heated as it flows through a tube with a diameter of 25 mm at a velocity of 10 m./sec. The

wall temperature is maintained constant and is 20°C above the air temperature all along the length of tube. Calculate:

(i) The rate of heat transfer per unit length of the tube.

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(ii) Increase in the bulk temperature of air over a 3 m length of the tube.

02. (i) Write down the momentum equation for a steady, two dimensional flow of an incompressible, constant property

newtonian fluid in the rectangular coordinate system and mention the physical significance of each term.

(ii) A large vertical plate 5 m high is maintained at 100°C and exposed to air at 30°C Calculate the convection heat

transfer coefficient.

03. (i) Sketch the boundary layer development of a flow over a flat plate and explain the significance of the boundary layer.

(ii) Atmospheric air at 275 K and a free stream velocity of 20 m/s flows over a flat plate 1.5 m long that is maintained at

a uniform temperature of 325 K. Calculate the average heat transfer coefficient over the region where the boundary

layer is laminar, the average heat transfer coefficient over the entire length of the plate and the total heat transfer rate

from the plate to the air over the length 1.5 m and width 1 m. Assume transition occurs at Ree = 2xl05

04. (i) What is Reynold's analogy? Describe the relation between fluid friction and heat transfer?

(ii) Air at 25°C flows over 1 m x 3 m (3 m long) horizontal plate maintained at 200°C at 10 mls. Calculate the average

heat transfer coefficients for both laminar and turbulent regions. Take Re (critical) = 3.5 x 105

05. (i) Define Reynold‟s, Nusselt and Prandtl numbers.

(ii) A steam pipe 10 cm outside diameter runs horizontally in a room at 23°C. Take the outside surface temperature of

pipe as 165°C. Determine the heat loss per unit length of the pipe.

06. (i) Explain for fluid flow along a flat plate:

(1) Velocity distribution in hydrodynamic boundary layer

(2) Temperature distribution in thermal boundary layer

(3) Variation of local heat transfer co-efficient along the flow.

(ii) The water is heated in a tank by dipping a plate of 20 cm X 40 cm in size. The temperature of the plate surface is

maintained at 100°C. Assuming the temperature of the surrounding water is at 30° C, Find the heat loss from the plate

20 cm side is in vertical plane.

07. Air at 400 K and 1 atm pressure flows at a speed of 1.5 m/s over a flat plate of 2 m long. The plate is maintained at a

uniform temperature of 300 K. If the plate has a width of 0.5 m, estimate the heat transfer coefficient and the rate of

heat transfer from the air stream to the plate. Also estimate the drag force acting on the plate.

08. Cylindrical cans of 150 mm length and 65 mm diameter are to be cooled from an initial temperature of 20°C by placing

them in a cooler containing air at a temperature of 1°C and a pressure of 1 bar. Determine the cooling rates when the

cans are kept in horizontal and vertical positions.

09. A circular disc heater 0.2m in diameter is exposed to ambient air at 25°C. One surface of the disc is insulated at 130°C.

Calculate the amount of heat transferred from the disc when it is.

(i) Horizontal with hot surface facing up

(ii) Horizontal with hot surface facing down (iii) Vertical

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10. (i) Distinguish between free and forced convection giving examples.

(ii) A steam pipe 10 cm OD runs horizontally in a room at 23° C. Take outside temperature of pipe as 165 ° C. Determine

the heat loss per unit length of the pipe. Pipe surface temperature reduces to 80° C with 1.5 cm insulation. What is the

reduction in heat loss?

UNIT – III PHASE CHANGE HEAT TRANSFER & HEAT EXCHANGERS


1. What is a Heat Exchanger1?

A device in which heat exchanges between the fluids by means of direct contact or indirect contact and allows fluid to

attain thermodynamic equilibrium.

2. How heat exchangers are classified based on direction of fluid flow?

Parallel flow , counter flow and cross flow heat exchangers

3. Give examples of non mixing type heat exchangers.

Radiators, Condensers, Evaporators

4. ketch temperature distribution graph for condensers & evaporators.

5. Define overall heat transfer coefficient.

The overall heat transfer coefficient is defined in terms of the total thermal resistance between two fluids. If there are a

number of thermal resistances between the two fluids, the overall heat transfer coefficient is given by: U = 1/ΣR

6. What is LMTD?

Determination of Mean temperature difference and expressed in terms of logarithmic relation.

7. What is effectiveness of a heat exchanger?

Qact/Qmax

8. Discuss the advantage of NTU method over the LMTD method.

Analysis can be done even without knowing the outlet temperatures of the leaving fluids.

9. What are the assumptions made during LMTD analysis?

„U‟ is uniform; PE and KE are negligible; Cp of the fluids is constant; Heat exchange takes place only between the

fluids

10. What are the factors are involved in designing a heat exchangers?

Heat transfer rate, size, weight, structural strength, pressure drop, cost etc.

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11. In what way Boiling & Condensation differs from other types of heat exchange?

These are surface phenomena.

12. What is Excess temperature in boiling?

TSuperheat- Tsat

13. What is meant by sub cooled or local boiling?

If the temperature of the liquid is below the saturation temperature the process is called local boiling.

14. What is nucleate boiling?

Formation of bubbles and raise to surface level is called Nucleate boiling.

15. Give expression for heat transfer coefficient in Nucleate boiling.

Refer the HMT data book

16. What is flow boiling?

Flow or force convection boiling may occur when a liquid is forced through a channel or over surface which is

maintained at a temperature higher than the saturation temperature of the liquid.

17. What is meant by condensation?

Whenever saturated vapour comes in contact with a surface at a lower temperature, the process of cooling is called

condensation.

18. Draw heat flux curve for various regions of flow boiling.

19. Define Film wise condensation.

Condensate wets the surface forming a continuous film which covers the entire surface.

20. Define Drop wise condensation.

Vapour condensates into small liquid droplets of various sizes which will fall down on the surface in a random fashion.

21. Your friend asserts that, in a heat exchanger, it is impossible for the exit temperature of the cold fluid to be greater than the exit temperature of the hot fluid when both fluids are single phase fluids. What is your response

The statement is true for a parallel flow heat exchanger. However, in a counter flow heat exchanger the outlet temperature of the cold fluid can in fact exceed the outlet temperature of the hot fluid.

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PART – B

01. A tube of 2 m length and 25 mm outer diameter is to be used to condense saturated steam at 100°C while the tube

surface is maintained at 92°C. Estimate the average heat transfer coefficient and the rate of condensation of steam if

the tube is kept horizontal. The steam condenses on the outside of the tube.

02. Steam condenses at atmospheric pressure on the external surface of the tubes of a steam condenser. The tubes are

12 in number and each is 30 mm in diameter and 10 m long. The inlet and outlet temperatures of cooling water flowing

inside the tubes are 25°C and 60°C respectively. If the flow rate is 1.1 kg/s, calculate

(i) The rate of condensation of steam

(ii) The number of transfer units

(iii) The effectiveness of the condenser.

03. (i) It is desired to boil water at atmospheric pressure on a copper surface which electrically heated. Estimate the heat

flux from the surface to the water, if the surface is maintained at 0°c and also the peak heat flux.

(ii) A tube of 2 m length and 25 mm OD is to be used to condense saturated steam at 100°C while the tube surface is

maintained at 92°C. Estimate the average heat transfer coefficient and the rate of condensation of steam if the tube is

kept horizontal. The steam condenses on the outside of the tube.

04. (i) Give the classification of heat exchangers.

(ii) It is desired to use a double pipe counter flow heat exchanger to cool 3 kg/s of oil (Cp = 2.1 kJ/kgK) from 120°C.

Cooling water at 20°C enters the heat exchanger at a rate of 10 kg/so The overall heat transfer coefficient of the heat

exchanger is 600 W/m2Kand the heat transfer area is 6 m2• Calculate the exit temperatures of oil and water.

05. (i) Discuss the general arrangement of parallel flow, counter flow and cross flow heat exchangers.

(ii) In a Double pipe counter flow heat exchanger 10000 kg/h of an oil having a specific heat of 2095 J/kgK is cooled

from 80°C to 50°C by 8000 kg/h of water entering at 25°C. Determine the heat exchanger area for an overall heat

transfer coefficient of 300 W/m2K. Take Cp for water as 4180 J/kgK.

06. (i) Discuss the various regimes of pool boiling heat transfer.

(ii) Dry saturated steam at a pressure of 2.45 bar condenses on the surface of a vertical tube of height 1 m. The tube

surface temperature is kept at 117°C. Estimate the thickness of the condensate film and the local heat transfer

coefficient at a distance of 0.2m from the upper end of the tube.

07. (i) With a neat and labeled sketch explain the various regimes in boiling heat transfer.

(ii) A vertical plate 0.5 m2 in area at temperature of 92°C is exposed to steam at atmospheric pressure. If the steam is

dry and saturated estimate the heat transfer rate and condensate mass per hour. The vertical length of the plate is 0.5

m. Properties of water at film temperatures of 96°C can be obtained from tables.

08. (i) Compare LMTD and NTU method of heat exchanger analysis.

(ii) Hot exhaust gases which enters a finned tube cross flow heat exchanger at 300°C and leave at 100°c, are used to

heat pressurized water at a flow rate of 1 kg/s from 35 to 125°C. The exhaust gas specific heat is approximately 1000

29

J/kg.K, and the overall heat transfer co-efficient based on the gas side surface area is Uh = 100W/m2K. Determine the

required gas side surface area Ah using the NTU method. Take Cp,c at Tc = 80°C is 4197 J/kg.K and Cp,h = 1000

J/kg.K .

09. Water is to be boiled at atmospheric pressure in a mechanically polished stainless steel pan placed on top of a heating

unit. The inner surface of the bottom of the pan is maintained at lO8°C. The diameter of the bottom of the pan is 30 cm.

Assuming Csf = 0.0130. Calculate (i) the rate of heat transfer to the water and ii) the rate of evaporation of water.

10. Define effectiveness of a heat exchanger. Derive an expression for the effectiveness of a double pipe parallel flow heat

exchanger. State the assumptions made.

11. Water enters a cross flow Heat exchanger (both fluids unmixed) at 5°C and flows at the rate of 4600 kg/h to cool 4000

kg/h of air that is initially at 40°C. Assume the over all heat transfer coefficient value to be 150 W/m2K For an

exchanger surface area of 25m2, Calculate the exit temperature of air and water.

12. (i) Describe the principle of parallel flow and counter flow heat exchangers showing the axial temperature distribution.

(ii) A parallel flow heat exchanger has hot and cold water stream running through it, the flow rates are 10 and 25

kg/min respectively. Inlet temperatures are 75° C and 25° C on hot and cold sides. The exit temperature on the hot

side should not exceed 50° C.Assume hi = ho = 600W/m2K. Calculate the area of heat exchanger using E -NTU

approach.

UNIT – IV RADIATION


1. What is a gray surface ?

A gray surface is defined as one for which the emissivity (e) and the absorptivity (a) are independent of wavelength (l).

2. What is a diffuse surface ?

A diffuse surface is defined as one for which the emissivity (e) and the absorptivity (a) are independent of direction (q).

3. Define a view factor.

A view factor is defined in the context of two surfaces A and B. It is defined as the fraction of radiation leaving A which is incident directly on surface B. A view factor must be defined in terms of surface A to surface B (FAB).

4.If a surface emits 200 W at a temperature of T, how much energy will it emit at a temperature of 2T?

Since E µ T4, a 2-fold increase of temperature brings a (2

4) = 16-fold increase in energy. Thus the surface will emit

(16)(200) = 3200 W.

5. You might have observed early morning frost on a clear day even when the minimum air temperature during the night was above 0° C. On a clear day, the effective sky temperature can be as low as -45° C. Explain how such frost formulation takes place.

The frost is created because of radiative losses to the sky

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6. A greenhouse has an enclosure that has a high transmissivity at short wavelengths and a very low transmissivity (almost opaque) for high wavelengths. Why does a greenhouse get warmer than the surrounding air during clear days ? Will it have a similar effect during clear nights ?

Solar radiation is skewed towards shorter wavelengths. On a clear day the glass of the greenhouse admits a large

proportion of the incident radiation. Inside the greenhouse, the various surfaces (plants etc.) reflect the radiation; but

the reflected radiation is spectrally different, having more of a high wavelength contribution. Thus the reflected radiation

is not transmitted well by the glass, and is reflected back into the greenhouse. The interior heats up due to this

'trapped' radiation. The same effect will not be seen on a clear night, since there is no solar radiation.

7. What is the difference between diffusion and radiation heat transfer ?

Diffusion heat transfer is due to random molecular motion. Neighboring molecules move randomly and transfer energy between one another - however there is no bulk motion. Radiation heat transfer, on the other hand, is the transport of heat energy by electromagnetic waves. All bodies emit thermal radiation. In particular, notice that unlike diffusion, radiation heat transfer does not require a medium and is thus the only mode of heat transfer in space. The time scale for radiative heat transfer is much smaller than diffusive heat transfer.

8. Define a black surface

A black surface is defined by three criteria:

it absorbs all radiation that is incident on it it emits the maximum energy possible for a given temperature and wavelength of radiation (according to

Planck's law) the radiation emitted by a blackbody is not directional (it is a diffuse emitter)

A black surface is the perfect emitter and absorber of radiation. It is an idealized concept (no surface is exactly a black surface), and the characteristics of real surfaces are compared to that of an ideal black surface.

9. What is the range of values for the emissivity of a surface ?

The emissivity ranges between 0 and 1.

10. What is Stefan's Boltzmann’s law?

Flux of heat energy emiited by tradiation from an ideal surface is proportional to its absolute temperature to the fourth

power.

11. What is Intensity of radiation?

Rate of heat flux emitted by it per unit projected area normal to the direction of radiation per unit solid angle.

12. Define Shape factor.

Fraction of the radiation energy that is diffused from one surface element and strikes the other surface directly with no

intervening reflections.

13. What is Radiation Shield?

To reduce the heat transfer by radiation between surfaces by effectively increasing the surface without actually

removing and heat from the overall system.

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14. Define Emissive power of a black surface.

Energy emitted by the surface per unit time per unit area.

15. Defme concept of Black body.

Its an ideal body that absorbs all incident energy and reflects or transmits none.

16. Define Planck's distribution law.

Refer HMT databook

17. Define Wien's distribution law.

Refer HMT databook

18. Define Emissivity of a surface.

It‟s a measure of hoe a surface emits radiant energy in comparison with a black surface at the same temperature.

19. What is meant by Kirchhoff's law?

At thermal equilibrium the ratio of the total emissive power to its absorptivity is the same for all bodies.

20. Define Irradiation.

The total radiation incident upon a surface per unit time and per unit area.

21. Define Radiosity.

Total radiation leaving the surface per unit time and per unit area.

22. Distinguish between Absorptivity & Transmittivity of radiation.

Fraction of amount absorbed by the surface is called Absorptivity

Fraction of amount transmitted from the surface is called Transmittivity.

23. What are the gases, which radiate heat?

CO,NO,CO2,H2O

24. What is mean by beam length in Gas Radiation?

when two surfaces are exchanging radiation through the intervening medium the length of the distance traversed by

radiation from different positions on the surface varies.

25. What is the equation for radiation between two gray bodies?

Refer HMT databook

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26. Differentiate Opaque body & perfectly transparent surface.

If transmissivity is Zero then its called as Opaque surface

If transmissivity is One then its called as Transparent surface

21. Write down the Wien's formula.

Refer HMT databook

22. Write down the heat transfer equation for Radiant exchange between infinite parallel gray planes.

Refer HMT databook

PART – B

01. Liquid Helium at 4.2 K is stored in a dewar flask of inner diameter = 0.48 m and outer diameter = 0.5 m. The dewar

flask can be treated as a spherical vessel. The outer surface of the inner vessel and the inner surface of the outer

vessel are well polished and the emissivity of these surfaces is 0.05. The space between the two vessels is thoroughly

evacuated. The inner surface of the dewar flask is at 4.2 K while the outer surface is at 300 K. Estimate the rate of heat

transfer between the surfaces.

02. A thin aluminium sheet with an emissivity of 0.1 on both sides is placed between two very large parallel plates that are

maintained at uniform temperatures Tl = 800 K and T2 = 500 K and have emissivities ε1 = 0.2 and ε2 = 0.7 respectively.

Determine the net rate of radiation heat transfer between the two plates per unit surface area of the plates and

compare the result to that without shield.

03. (i) Discuss how the radiation from gases differ from that of solids.

(ii) Two very large parallel plates with emissivities 0.5 exchange heat. Determine the percentage reduction in the heat

transfer rate if a polished aluminium radiation shield of c = 0.04 is placed in between the plates.

04. (i) Define emissivity, absorptivity and reflectivity .

(ii) Describe the phenomenon of radiation from real surfaces.

05. (i) What are the radiation view factors and why they are used?

(ii) Determine the view factor (F1-4) for the figure shown below.

06. (i) State and prove the following laws: (1) Kirchoffs law of radiation

(2) Stefan - Boltzmann law.

(ii} Show-from energy-balance consideration that the radiation heat transfer from a plane composite surface area A4

and made up of plane surface areas A2 and A3 to a plane surface area Al is given by: A4F41=A3F31+A2F21 &

F14=F12+F13

07. (i) Using the definition of radiosity and irradiation prove that the radiation heat exchange between two grey bodies.

33

(ii) A surface at 100K with emissivity of 0.10 is protected from a radiation flux of 1250 W/m2 by a shield with emissivity

of 0.05. Determine the percentage cut off and the shield temperature. Assume shape factor as 1.

08. Explain briefly the following: (i) Specular and diffuse reflection (ii) reflectivity and transmissivity (iii) reciprocity rule and

summation rule.

09. (i) Two parallel, infinite grey surface are maintained at temperature of 127C and 227C respectively. If the temperature

of the hot surface is increased to 327°C, by what factor is the net radiation exchange per unit area increased? Assume

the emissivities of cold and hot surface to be 0.9 and 0.7 respectively.

(ii) Two equal and parallel discs of diameter 25 cm are separated by a distance of 50 cm. If the discs are maintained at

600°C and 250°C. Calculate the radiation heat exchange between them.

10. Two large parallel planes with emissivities 0.35 and 0.85 exchange heat by radiation. The planes are respectively

1073K and 773K . A radiation shield having the emissivity of 0.04 is placed between them. Find the percentage

reduction in radiation heat exchange and temperature of the shield.

UNIT – V MASS TRANSFER


1. What is meant by mass transfer?

The process of transfer of mass as a result of the species concentration difference in a mixture is called mass transfer.

2. What is Diffusion mass transfer?

Mass can be transferred by random molecular motion in quiescent or laminar flowing fluids.

3. What is Convective mass transfer?

Mass can be transferred from a surface whenever the concentration of some species at the surface differs from its

concentration in a gas flowing over the surface.

4. Give some examples of Diffusion mass transfer.

Sugar added in a copy, transfer of water vapour into dry air

5. What is the governing equation for Diffusion mass transfer?

Refer HMT databook

6. What is mass diffusion velocity?

The velocity of a component relative to the mass average velocity of the mixture.

7. What is the Molar Diffusion velocity?

The velocity of a component relative to the molar average velocity.

34

8. Define the following: Ii) Mass concentration b) Molar concentration

Mass concentration: Mass per unit volume of the mixture

Molar concentration: The number of moles of species per unit volume of the mixture.

9. What is Counter diffusion?

Each molecule of A is replaced by a molecule of B and vice versa while the total pressure is uniform throughout.

10. Define mass fluxe.

Amount of the species which crosses a given area per unit time.

11. What is the governing equation for Transient Diffusion?

Refer HMT databook

12. Give equation for Counter diffusion.

Refer HMT databook

13. Define Fourier number & Biot number for mass transfer.

Refer HMT databook

35

PART – B

01. A steel sphere of radius 60 mm which is initially at a uniform temperature of 325°C is suddenly exposed to an

environment at 25°C; with convection heat transfer coefficient 500 W/m2K. Calculate the temperature at a radius 36

mm and the heat transferred 100 seconds after the sphere is exposed to the environment.

02. The tire tube of a vehicle has a surface area 0.62 m2 and wall thickness 12 mm. The tube has air filled in it at a

pressure 2.4 x 105 N/m

2• The air pressure drops to 2.3 x 10

5 N/m

2 in 10 days. The volume of air in the tube is 0.034 m

3•

Calculate the diffusion coefficient of air in rubber at the temperature of 315K. Gas constant value = 287. Solubility of air

in rubber tube = 0.075m3 of air/m3 of rubber tube at one atmosphere.

03. (i) Define mass concentration, molar concentration, mass fraction and mole fraction.

(ii) The diffusivity of CCl4 in air is determined by observing the steady state evaporation of CCl4 in a tube of 1 cm

diameter exposed to air. The CCl4 liquid level is 10 cm below the top level of the tube. The system is held at 25°C and

1 bar pressure. The saturation pressure of CCl4 at 25°C is 14.76 kPa. If it is observed that the rate of evaporation of

CCl4 is 0.1 kg/hour determine the diffusivity of CC14 into air.

04. (i) Dry air at 20°C (p = 1.2 kg/m3, v = 15 x lQ-6 m2/s, D = 4.2 x lQ-5 m2/s) flows over a flat plate of length 50 cm which

is covered with a thin layer of water at a velocity of 1 m/s. Estimate the local mass transfer coefficient at a distance of

10 cm from the leading edge and the average mass transfer coefficient.

(ii) Discuss the analogy between heat and mass transfer.

05. (i) A mixture of 02 and N2 with their partial pressures in the ratio 0.21 to 0.79 is in a container at 25°C. Calculate the

molar concentration, the mass density, the mole fraction and the mass fraction of each species for a total pressure of 1

bar. What would be the average molecular weight of the mixture?

(ii) Discuss the analogy between heat and mass transfer.

06. (i) Explain Fick's first and second laws of diffusion.

(ii) Explain the phenomenon of equimolar counter diffusion. Derive an expression for equimolar counter diffusion

between two gases or liquids.

07. (i) Define the Schmidt ,Sherwood and Lewis numbers. What is the physical significance of each?

(ii) Dry air at 27°C and 1 atm flows over a wet flat plate 50 cm long at a velocity of 50 mls. Calculate the mass transfer

co-efficient of water vapour in air at the end of the plate. Take the diffusion coefficient of water vapour in air is DAB =

0.26 X 10-4

m2/s.

08. Discuss briefly the following

(i) Fick‟s law of diffusion

(ii) Equimolar counter diffusion

(iii) Evaporation process in the atmosphere

09. (i) What are the assumptions made in the I-D transient mass diffusion problems?

36

(ii) An open pan, 20 cm diameter and 8 cm deep contains water at 25°C and is exposed to dry atmospheric air.

Estimate the diffusion coefficient of water in air, if the rate of diffusion of water is 8.54X 10-4

kg/h

10. C02 and air experience equimolar counter diffusion in a circular tube whose length and diameter are 1m and 50mm

respectively. The system is at a total pressure of 1 atm and a temperature of 25°C. The ends of the tube are connected

to large chambers in which the species concentrations are maintained at fixed values. The partial pressure of CO2 at

one end is 190mm of Hg while at other end is 95mm of Hg. Estimate the mass transfer rate of C02 and air through the

tube. The diffusion coefficient for C02 - air combination is 0.16 x 10-4

m/s.

11. (i) Define the non dimensional numbers in mass transfer

(ii) Dry air at 27C and 1 atm flows over a wet flat plate 50cm long at a velocity of 50m/sec. Calculate the mass transfer

co-efficient of water vapour in air at the end of the plate. Take D=O.26x10-4

m2/sec. β = 1.1614 kglm

3 ;μ = 184.6 10

-7

Ns/m2 Pr = 0.707

12. Atmospheric air at 40° C flows over a wet bulb thermometer and it shows 25° C. Calculate the concentration of water

vapour in the free stream and also its relative humidity. Take D (air-water) = 0.256 x 1O-4m

2 Is. If temperatures of dry

and wet bulb are 30° C and 25° C respectively. What would be the corresponding values?

37

SUBJECT NAME: MANUFACTURING TECHNOLOGY

UNIT- I THEORY OF METAL CUTTING


1. What are the different types of chips?

1. Continuous chips

2. Discontinuous chips

3. Discontinuous with built up chip

2. What is Rake angle?

The angle made by the cut chip with the tool face is called rare angle.

3. What is shear angle?

The angle made by the tool more cutting edge with the uncut chip is called shear angle.

4. What is orthogonal cutting?

The angle made by the tool to the cutting directions of the metal is 90 is called orthogonal cutting.

5. What is chip thickness ratio?

Chip thickness ratio is defined as the ratio of uncut chip thickness to cut chip thickness

t

r = -------

tc

6. What are fore acting as the cutting of a metal?

1. Horizontal cutting fore Fc 2. Tangential cutting fore Ft 3. Shear fore Fs 4. Normal fore Fn

7. What are the properties required for cutting tool material.

1. Higher hardness 2. Hot hardness 3. Wear resistance 4. Toughness 5. Low friction 6. Better thermal characteristics

38

8. What are the tool materials?

1. Carbon tool stretch 2. H.S.S. 3. Cast cobalt Alloys 4. Cemented carbides 5. Ceramic tools 6. Diamond 7. Cubic boron

9. What are the types of tool wear ?

1. Flank wear 2. Crater wear

10. What is flank wear?

Wear as the flank fare.

11. What is orater wear?

The wear on the fond face of the tool

12. What is tool life?

Useful life of the tool experienced in time units.

13. What is a tool life equation?

VT = C

14. What is machinobility ?

It is the characteristics of work material enpressing its ease of machining.

15. What are the variables that affects tool life?

1. Cutting conditions 2. Tool geomentry 3. Tool material 4. Ware materials 5. Cutting fluid

16. What are the factors that affect surface finish?

1. Geomentry of the machining operations 2. no of uncomfortable factors

39

17. What are the functions of a cutting fluid?

1. Cool the tool and work piece 2. reduce friction 3. protect the work against mushing 4. improve surface finish 5. to prevent the formations of surface finish 6. wash away the chips

18. How will you select a cutting fluid?

1. Work piece material 2. Machining operations 3. Cutting tool material

19. How are the ceramic tools are made?

Ceramic tools are moulded as powder metallurgy principle.

20. What are the points from which cutting fluid may be applied?

Tool are to be engaged in cutting.

PART-B 1. Explain orthogonal cutting and oblique cutting with its neat sketches and compare. (16) 2. What is the tool life equation and state the factor affecting the tool life. 3. What is machinability? And explain. 4. Explain the various tool materials. 5. Write short notes on surface finish. 6. What are the different types of cutting fluids used in machining process? 7. Write short notes tool wear. (16)

UNIT- II CENTRE LATHE & SPECIAL PURPOSE LATHES


1. What is centre lathe?

The center of the head shock and tail shock are in the same centre that is why it is called as center lathe.

2. Mentions the Lathe parts ?

1. Head shock 2. Tail shock 3. Carriage 4. Tool post

3. What are the types of lathes?

1. Center lathe 2. Tool room lathe 3. Special pumps lathe 4. Capstan and 5. Automatic lathe

40

4. What is the function of a lead?

It will guide the carriage.

5. What is the use of Bed way (or) Guide way?

It gives straight line accuracy to the tail shock and carriage etc.,

6. What are the work holding devices?

1. Three jaw chuck 2. Four jaw chuck 3. Fare plate

7. What is the tool holding device available in center lathe?

Tool post is the tool holding device.

8. What is the difference between three jaw chuck and Four jaw chuck?

Three jaw is a independent chuck

Four jaw is a self dependent chuck

9. What is line center and deed center of center lathe?

Head shock is the line center because power is used to rotate spindle.

10. What is a Mandrel?

Mandrel is an element used in lathe by turning hallow tubes.

11. What is single point cutting tool?

The cutting tip of a point is single edge.

12. What is nose radius?

The radius of the cutting tip is called nose radius.

13. What is relief angle?

The recess provided in all the sides of the cutting edge is called relief angles.

14. What is back rake angle?

The recess provided in the flank of the tool face is called back rake angle.

15. What are the tools used in lathe?

1. Parting off tool 2. Turning tool 3. Radius tool 4. Thread cutting tool 5. Chamfering tool

41

16. What are the operations performed on a lathe?

1. Turning 2. Facing 3. Chamfering 4. Threading

17. How drilling operation is performed on lathe?

The drill bit is held in tail shock and the wall piece is chuck. The drilling operation can be held.

18. How taper turning can be done is lathe ?

By using compound rest.

19. What is formula for cutting speed?

TDN

V = ----------

1000

20. What is formula for machining time calculation in lathe?

L + Lo

t = ---------

FN

L = Length of job

Lo = Over travel of the tool

F = feed rate mm /

N = rpm

PART-B 1. Sketch a center lathe and mention various parts. (16) 2. List various types of feed mechanisms and explain briefly about tumbler gear reversing mechanism with sketch. (16) 3. Explain taper turning operation in a lathe by a taper turning attachment. Discuss its advantages. 4. Explain the following methods of taper turning in a lathe. 5. (i) By swiveling the compound rest.

(ii) By a taper turning attachment. 6. Explain the Working principle of capstan and turret lathes. 7. Explain the tooling layout for the production of a Hexagonal bolt in a capstan lathe. (16) 8. Discuss the tooling layout for the production of a Hexagonal nut in Turret lathe. 9. Classify transfer machines. Sketch and explain the working of Swiss type automatic screw machine. What are the

advantages of automatic machines? (16) 10. Describe a typical single spindle automatic chucking machine. 11. Describe a typical single spindle automatic bar machine. 12. Differentiate between parallel action and progressive action multi-spindle automatics. (16)

42

UNIT-III OTHER MACHINE TOOLS


1. What are Reciprocating machines ?

1. Shaper 2. Planner 3. Slotter

2. What is cutting shock of a shaper ?

The forward shock is called cutting shock.

3. What is quide return mechanism ?

The reversal of the ram is faster than the cutting shock.

4. What is principle of shaper ?

The tool reciprocates against fired job.

5. What is work holding device used in sneper ?

Machine vice

6. What are the operations can be done on shaper?

1. Squaring 2. Angle machining 3. „V‟ groove cutting 4. dovetail cutting

7. Whare the types of planner ?

1. Double housing planner 2. Pit planner 3. Single housing planner

8. What are the operations can be performed on the planner?

1. Angle machining 2. Dovetail machining 3. „V‟groove machining

9. What is the principle of planner?

The work reciprocates and tool fixed.

10. What is the principle of shorter ?

Vertical reciprocation of tool and fixed job.

43

11. What are the operations can be done on shorter?

1. Internal key ways 2. Slot 3. Polyson cutting etc.,

12. What are milling operations?

1. Slab milling 2. Face milling 3. end milling 4. form milling

13. What are the drilling machines available?

1. Bench drilling 2. Radial drilling 3. Crang drilling

14. What is Boring operation?

Enlarging a hole is called boring.

15. What is Reaming operation?

It is finishing of holes.

16. What is tapping?

Cutting threads is the hole by using a die.

17. What is the difference between Lack saw and Circular saw?

The Lack saw reciprocates and cuts the job.

Circular saw rotates to cut the job.

18. What is Broaching?

It is finishing of holes, keyways etc.,

19. What are the types of broaching?

1. Push type 2. Pull type

20. What is spot facing ?

Finishing of holes face in the top of the hole.

PART-B

1. With a simple sketch, explain the working of the crank and slotted link quick return motion mechanism used in shaper. 2. Write down any four differences between shaper and planer. 3. Explain the Working principle of planer with a neat sketch.

44

4. How do you specify a planer? 5. Describe the working mechanism of a universal dividing head, with neat diagram. (16) 6. With a neat sketch, indicate the various parts of an arbor assembly.(16) 7. With a simple sketch, explain the principal parts and angles of a plain milling cutter .Explain them. (16) 8. Explain the twist drill nomenclature and define various elements of twist drill. 9. With a simple sketch, explain the working of a vertical boring machine. 10. Explain the counter boring and counter ringing operation. 11. Explain the Working principle of a Jig boring machine with a neat sketch. (16)

UNIT-IV ABRASIVE PROCESSES & GEAR CUTTING


1. What are the abrasives used in grinding?

1. Aluminium oxide 2. Silicon carbide 3. Cubic Nitride (LBN)

2. What is Grain size?

The abrasive used in grinding wheel is relatively small. The size of the abrasive grain is called grain size.

3. What is Bond?

The barding of abrasive grains is called bond.

4. What are types of bond?

1. Vetrified 2. Silicate 3. Synthetic resin 4. Rubber 5. Shellac and Metal

5. What are the Grades of Grinding wheel?

1. Very soft 2. Medium 3. hard

6. How are grinding wheels are balanced?

The grinding wheels are

Static balancing

Dynamic balancing

7. What are the difference shapes of grinding wheel?

1. Straight 2. Cutoff 3. Recessed one side 4. Recessed two side 5. Dish 6. Saucer

45

8. What is dressing and Truing?

The grinding wheel is consumed to the operation on a job. Because of this the wheel is tuned to certain diameter.

9. What are the types of Grinding machines?

1. Cylindrical grinding machines 2. Surface grinding machines 3. Center less grinding machines

10. What are the parameters that affect Grinding process?

1. Wheel speed 2. Work speed 3. In feed 4. Area of contract

11. What are the super finishing operations available?

1. Honing 2. Lapping 3. Buffing etc.,

12. What is super finishing?

Finishing the component by removing micron level materials.

13. What is abrasive jet machining?

The abrasive with water jet is used to machine plastic, leather components.

14. Why gears are important?

The power transmitting belt has ship and gears are no ship positive drive.

15. How gears are cut?

1. Gear shaping 2. Gear generation

16. What is gear shaping?

The cutting of gear by form tool.

17. What is gear hobbing ?

Cutting gears with the help of a hob called cutter.

18. What is module of a gear ?

D

M = -------

Z

46

D = Dia of blank

Z = no of teeth

M = Module

19. What is gear forming?

The gear cut by the form cutters is called gear forming.

20. What for gears are used?

1. Power transmissions 2. Motion transmission

PART-B

1. What are the various methods of centerless grinding and each briefly? (16) 2. Explain the external cylindrical grinding process and surface grinding process. 3. Explain the vitrified and resinoid bonding process. 4. Explain the operations of horizontal broaching machine with neat sketch. 5. Explain the gear cutting by a formed tool. 6. Differentiate between gear forming and generating. 7. Explain the principle of operation of gearing hobbing operation what are the advantages of gear hobbing. 8. Give advantages and limitations of gear hobbing.

UNIT- V CNC MACHINE TOOLS & PART PROGRAMMING


1. What is NC machines ?

Numerically controlled machines are called NC Machines

2. What is the difference between NC and CNC machines ?

NC – Machines tape header is available

CNC - Computer memory is available

3. What are the steps to be followed while developing the CNC program?

1. Process planning 2. Tool selection 3. Job, Tool setup 4. Part program

4. What are the process plans content ?

1. Machine tool used 2. Fixture required 3. Sequence of operation 4. Cutting tools used 5. Process parameters 6.

47

5. What is point programming?

The drilling operations can be carried on point by point it is called point programming.

6. What is curve forming programming?

The program to trace a path is called curve programming.

7. What is preparatory function?

The „G‟ codes are called as preparatory functions.

8. What is miscellaneous function?

The „M‟ codes which controls machines.

9. What is the function o ‘GOO’ ?

Rapid traverse.

10. What is GO1 stand for ?

Liner interpolation

11. What is GO2 stands for ?

Circular interpolation.

12. What is G41 stands for ?

Cutter compensation left.

13. What is G40 stands for ?

Cutter compensation.

14. What is G76, G70, G71 ?

G76 – Thread Cutting cycle

G70 – Finishing cycle

G71 – Roughing cycle

15. How many axis available is lathe?

Only two X, Z

16. How many axis available in mining?

X,Y,Z Three axis.

48

17. What are the core machines available?

1. Horizontal machining center 2. Vertical machining center 3. Multi axis machining center

18. Why core machines are preferred?

1. Accuracy 2. Productivity etc.

19. What are the parts of core machines?

1. Slide way 2. Linear bearings 3. Servo motor 4. Fanure systems

20. What are the types of system available?

1. Fanure system 2. Hinumeric system 3. Sinumeric system 4. Siemens system

PART-B

1. List the various drive systems explain the principle of any two drive system. 2. Explain open loop and closed loop system. 3. What is machining centers explain in detail. 4. Explain various types of CMM. 5. Explain the part programming procedure with a good example. 6. List and explain G and M code for turning milling operations. 7. Explain NC axis conventions.

49

SUBJECT NAME: ENGINEERING MATERIALS AND METALLURGY

UNIT I


1. Define Solid solution.

Two metals combined together to form a single structure

2. Name the two kinds of Solid Solutions

Substitutional

Interstitial

3. How the substitutional Solutions are formed.

When the Solute atoms replace Solvent atoms

4. How the Interstitial Solutions are formed.

When the Solute atoms are small enough to occupy the holes between the Solvent atoms

5. What are the factors governing Solid solubility?

Crystal structure

Relative atomic size

Chemical affinity

Valency

6. What is Phase diagram?

The phase diagram indicates the temperature at which the solid alloy will start melting and finish melting.

7. What are the types of phase diagrams?

Unary

Binary

Ternary

8. What are the Coordinates of phase diagram?

Temperature and Time

9. What is Isomorphous Reactions?

Two metals that is completely soluble in Liquid state and solid state.

10. Give some examples of Isomorphous alloy systems.

Copper and nickel

Gold and silver

Iron and vanadium

11. What is Eutectic Reactions?

Two metals that are completely soluble in Liquid state and partly or insoluble in the solid state

12. Give the Reaction happening in Eutectic?

Liquid àSolid 1 + Solid 2

50

13. What is Peritectic Reactions?

Liquid + Solid 1 àSolid 2

14. What is Eutectoid Reactions?

This reaction is due to the transformation in solid state

15. Give the Reaction taking place in Eutectoid?

Solid 1 à Solid 2 + Solid 3

16. Write an example of the eutectoid reaction occurs in the Iron Carbon System

Austenite à Ferrite + Cementite

17. What is Peritectoid Reactions?

This reactions is due to the transformation of two Solids in to third solid state

18. Give the Reaction taking place in Peritectoid ?

Solid 1 + Solid 2 à Solid 3

19. Why Iron-Iron Carbide diagram is important ?

It is the most important binary alloy system in engineering alloys because we get important alloys Cast Iron and steel.

20. What is the content of steel?

It contains 0.008% to 2.14 wt% C in Fe.

21. What is the content of Cast Iron?

It contains 2.14% to 6.7 wt% C in Fe.

22. What are the two-phase diagrams of Iron-carbon system?

Fe – Fe 3 C

Fe - C

Here Fe – Fe 3 C is the portion of Fe – C phase diagram.

23. What are the four solid phases in the iron-iron carbide diagram?

1. d -Ferrite

2. Austenite (g)

3. Cementite

4. a -Ferrite

24. What are the reactions taking place in the Iron-Carbide diagram?

Peritectic

Eutectic

Eutectoid

25. What is the Peritectic reaction in Iron-Carbide diagram?

d -Ferrite + Liquid à Austenite (g)

26. What is the Eutectic reaction in Iron-Carbide diagram?

Liquid à Austenite (g) + Cementite

27. What is the name of this combination Austenite (g) + Cementite?

51

Ledubrite

28. What is the Eutectoid reaction in Iron-Carbide diagram?

Austenite (g) à a -Ferrite + Cementite

29. What is the name of this combination a -Ferrite + Cementite?

Pearlite

30. What is Hypoeutectoid and Hypereutectoid steeel?

A composition Left to the Eutectoid Composition is Hypoeutectoid

A composition Right to the Eutectoid Composition is Hypereutectoid

31. Write the classification of steel ?

Low carbon

Medium carbon

High Carbon

Tool steel

31. How the steel classified?

According to the carbon content in Fe.

32. What are the types of Cast iron?

Gray

Nodular

White

Malleable

PART B

1. Discuss the similarities and differences between substitutional and interstitial solid solutions.(Refer Page No:1.5 -1.8 in

V.Jayakumar and Intro to physical metallurgy ,SYDNEY AVNER)

2. Explain the following invariant reactions with reference to a phase diagram:

(a). Eutectic reaction, (b) Eutectoid reaction,

(c) Peritectic reaction, and (d) Peritectoid reaction.( Refer Page No 1.34-1.39 in V.Jayakumar and Intro to physical

metallurgy ,SYDNEY AVNER)

3. What are the micro-constituents of iron- carbon alloys? Explain the general characteristic of each. (Refer Page No

1.47-1.51 in V.Jayakumar and Intro to physical metallurgy ,SYDNEY AVNER)

4. Draw iron-iron carbide equilibrium diagram and mark on it all salient temperatures and composition fields.( Refer Page

No 1.52-1.56 in V.Jayakumar and Intro to physical metallurgy ,SYDNEY AVNER)

5. Explain the primary crystallisation of eutectoid steels, hypoeutectoid steels, and hypereutectoid stells.( Refer Page No

1.57-1.62 in V.Jayakumar and Intro to physical metallurgy ,SYDNEY AVNER)

52

UNIT – II


01. What is Heat treatment of metal?

Combination of heating, holding and cooling

02. Write some objectives of Heat treatment?

1. To Relieve internal stresses

2. To improve Machinability

3. To improve the properties

03.What are the types of heat Treatment?

Annealing

Normalising

Hardening

Tempering

03.What are the types of Annealing?

Full

Stress-relief

Recrystallization

Spheroidizing

Process

04. What is the process in Full Annealing?

Heating the steel 15 0 to 40 0 C above A3 temperature

Now the steel is Austenized

Cooling very slowly in the furnance itself

05. What is the process in Stress relief annealing?

Heating the steel up to 600 degree C


Cooling very slowly in the room temp in air

06. What is the process in Recrystallization or process annealing?

Heating the steel 600 to 650 degree C


Cooling very slowly in the room temp in air

07. What is the Spheroidizing?

The cementite is hard to machine because of its needle like structure

So heated to about 700 degree C. Now the Cementite becomes globular structure

53

Called Spheroids which will be easy to machine.

08. What is Normalising?

Annealing Heat tretment process called normalizing.

Heating the steel 55 0 to 85 0 C above A3 temperature

Hold for 15 minutes. Now the steel is Austenized

Cool down in still air

09. What is the purpose of normalizing?

To refine the grain size

To produce more uniform and desirable size distribution.

10. what is the abbrevation of TTT-diagram?

Time,Temperature and Transformation of Austenite.

11.what are the other names of TTT diagram?

Isothermal Transformation(IT-diagram) curves and S-curve,C-curve due to their shapes

12. How to obtain IT – diagram?

Normally upon cooling austenite transforms to Pearlite(ferrite + cementite)

13.what are the co-ordinates of IT-diagram?

Amount of Austenite transformed in vertical axis(Y-axis)

Time(Logirathamic scale,so we can use for days,weeks,months) in X-axis

14. What are the products you came to know from IT-diagram?

AT 700 0 C Coarse Pearlite

AT 600 0 C upper Bainite ( Sorbite )

AT 500 to 550 0 C Fine Pearlite(Troosite)

AT 550 to 300 0 C Lower Bainite (acicular troosite)

15. What is Hardness?

Resistance to plastic deformation

16. What is Hardening?

Hardening is process in which the metal is heated to the austenizing temp and suddenly

cooled in cold water.

17. What is the reason for Hardening?

Martensite is formed from Austenite directly .This is a complex structure formed due

to sudden cooling.

18. What is Tempering?

In Hardening the metal becomes too brittle and with lot of internal stresses which would affect the property of metal. To

remove this and to get desired property we reheat the hardened metal.this process is called Tempering.

19. What is Martempering?

If we reheat the after Martensite formation

54

20. What is Austempering?

Transformation directly to Bainite formation

21. What are the three types of Tempering?

Low temperature

High temperature

Medium Temperature

22. What are the types of hardening process?

Work Hardening

Age Hardening

Air Hardening

Hardening by heating and quenching

23. What is Hardenability?

Penetration of Hardness in the metal

24. What is the test to find Hardenabilty?

Jominy Quench Test

25. What is case hardening?

The surface of the steel is more hard and wear resistant whereas the core remains soft and tough.

Example: in gears, ball bearings

26. What are the various types of case Hardening?

Carburizing, Cyaniding, Nitriding, Flame and Induction Hardening

PART B

1.Compare and contrast the process of full annealing, process annealing, stress relief annealing, recrystallisation

annealing, and spheroidise annealing.( Refer Page No 2.4-2.11 in V.Jayakumar and Intro to physical metallurgy

,SYDNEY AVNER)

2. (a) Describe the normalising process of heat treatment (Refer Page No 2.11-2.12 in V.Jayakumar and Intro to physical


(b) Differentiate between normalising and full annealing (Refer Page No 2.12-2.13 in V.Jayakumar and Intro to physical


3. Explain the process of martempering compare and contrast it with austempering process (Refer Page No 2.21- 2.25 in


4. (a)What do you understand by isothermal transformation?

(b) What are TTT diagrams?

(c) How a TTT diagram is drawn?

(d) Draw a neat sketch of the TTT diagram for a eutectoid steel and label the regions,. Mark the different products

formed on this diagram.( Refer Page No 2.27-2.33 in V.Jayakumar) and Intro to physical metallurgy ,SYDNEY AVNER)

55

5. What is meant by carburising of steel? Briefly explain the various types of carburising(Refer Page No 2.50-2.56 in

V.Jayakumar) and Intro to physical metallurgy ,SYDNEY AVNER)

UNIT – III


1. What is alloy steel?

Steel in which other elements are added other than carbon.

2. What are the effects of alloying additions on steel?

To increase Strength, Hardness, Toughness, Properties

3.How stainless steel divided?

Martensitic, Ferritic , Austenitic

4. What are the various types of Tool steels?

Plain carbon

Low alloy

High speed

High Chromium High Carbon steels

5. What is HSLA steels?

High Strength low alloy steels, which have, better mechanical properties.

6.What are Maraging steels?

Martensite aging. Steels with greater Tensile strength (ultra high strength steels)

7.What are the tests conducted in the material?

Impact test,hardness test,shear test,tensile test,fatigue test,creep test

8. What is fatigue fracture?

It is the fracture that occurs under repeatedly applied fatigue stresses

9. What is Brittle fracture?

It takes place with minimum of plastic deformation and very rapid crack propagation.

10. What is creep fracture?

It is the fracture that takes place due to excessive creeping of metals

under steady loading and high temperature.

11. What is the need of mechanical test?

Inorder to determine which material is best by knowing the properties such as hardness,ductility,Strength.

56

PART B

1. (a)Give the classifications of steels.( Refer Page No 3.8 in V.Jayakumar)

(b) Describe the properties and typical applications of low medium, and high- carbon steels;( Refer Page No 3.3-3.11 in

V.Jayakumar)

(c) What is an alloy steel? how are alloy steels classified? Explain them.( Refer Page No 3.13- 3.15 in V.Jayakumar

and Intro to physical metallurgy ,SYDNEY AVNER

2. (a)What are the main classifications of stainless steels?

(b) Discuss the different types of stainless steel, making reference to approximate compositions, structures, heat

treatments.

(c)Give typical applications for each of the main catetgories of stainless steel.( Refer Page No 3.22-3.28 in


3. (a) Explain the principle characteristics pf cast iron and explain the factors which affect the structrure of cast iron.(

Refer Page No 3.37-3.40 in V.Jayakumar)

(b) Describe the structures of the main types of cast irons and account for their continued use as engineering

materials.( Refer Page No 3.41-3.48 in V.Jayakumar)

c) Compare grey and malleable cast irons with respect to (i) composition and heat treatment,(ii)microstructure, and

(iii) mechanical characteristics.( Refer Page No 3.48-3.51 in V.Jayakumar)

(d) Compare white and nodular cast irons with respect to (i) composition and heat treatment,(ii) microstructure, and (iii)

mechanical characteristics.( Refer Page No 3.51-3.56 in V.Jayakumar)

4. Discuss the composition,Properties, and typical applications of any four copper alloys.( Refer Page No 3.59-3.69 in

V.Jayakumar)

UNIT –I V

PART - A

01. How copper alloys classified?

Copper-Zinc

Copper-Tin

02.what are the types of bronze?

Phosphorous

Silicon

Beryillium

Manganese

Aluminium

03. What are the three main steps in precipitation Strengthening treatment?

Solution Treatment

57

Quenching

Aging

04. How the metals are classified?

Ferrous (Iron-based)

Non-Ferrous (non Iron-based)

05. What are the two types of Deformation in metals?

Plastic Deformation

Elastic Deformation

06. What is plastic deformation?

When a body is subjected to a force, it will tend to deform. When the

deformation exceeds the elastic limit it will not regain to its original form

07. What is Elastic deformation?

When a body is subjected to a force, it will tend to deform. When the

deformation with in the elastic limit it will regain to its original form

08 In what ways plastic deformation takes place?

Two methods

1.Slipping

2.Twinning

09.Deine slipping.

It is defined as the shear transformation, which moves the atoms over a number of

interatomic distances relative to their initial position.

10.Define Twinning.

It is the two plastic deformations which takes place along two planes due to set of forces

acting on a given metal.

11.Define fracture.

Seperation of Solids in to two Parts.

12. What are the two components of the p[rocess of fracture?

Crack initiation

Crack propagation

13. What are the different types of fracture

Brittle

Ductile

Fatigue

Creep

58

14. What is the use of izod test?

To determine the impact strength of the material

15.What is the yield strength?

The material yield with out a change in the load

PART B

1. Explain the composition, properties, and typical applications of some aluminium alloys.( Refer Page No 3.68-3.70 in

V.Jayakumar)

2. What do you understand by polymerisation? with th help of suitable examples, compare and condensation

polymerisation.( Refer Page No 4.10-4.14 in V.Jayakumar/Engineering Materials by Kenneth G. Budinski/Sydney H

Avener)

3. (a)Describe the difference between thermoplastics and thermosetting plastics.( Refer Page No 4.20-4.21 in

V.Jayakumar/Engineering Materials by Kenneth G. Budinski/Sydney H Avener)

(b) Explain the difference between commodity plastics and engineering plastics.( Refer Page No 4.21-4.22 in


4. What are Ceramics? List and briefly explain five important properties of Ceramics that make them useful engineering

materials.( Refer Page No 4.52-4.55 in V.Jayakumar/Engineering Materials by Kenneth G. Budinski/Sydney H Avener)

5. Discuss the properties and typical applications of the following engineering Ceramics:

(a)Alumina (b)SiC (c)silicon nitride (d)PSZ and (e) Sialons (Refer Page No 4.56-4.65 in


6 (a).what is the Distintion between matrix and dispersed phases in a Composite material? ( Refer Page No 4.66-4.68 in


(b)Contrast the mechanical characteristics of Matrix and dispersed phases for fibre-reinforced composites.(4.75 in

V.Jayakumar/Sydney H Avener)

59

UNIT – V


01. Define the term polymer.

Poly-many

Mer-single unit

Polymer – many units joined together

02. What are the naturally occurring polymers?

Wood,rubber,leather etc.

03.What are the synthetic polmers?

Nylon,Terlyene,Poly ethylene ….

04. What is polymerization?

Small molecules combine to form large molecule.

05. What are the types of polymerization?

1. Addition

2. Condensation

06. What is the difference between Addition and condensation polymerization?

Addition – no by product formed

Condensation –by product formed

07.How are polymers classified?

Thermoplasts, Thermosets

08. What is the difference between Thermoplasts and Thermosets?

Thermosets cannot be remoulded

Thermosets can be remoulded

09. Define ceramics?

Ceramics are compounds of metallic and non-metallic elements. Ex: stone,brick,clay,glass

10.What does new ceramic material include?

Oxcides,carbides ,borides and other similar compounds

11. Name two refractory materials.

Magnesia

Alumina

12. What is composite material?

Two or more materials with superior properties combined together to form new product.

13. Write an example for composite material?

Cement concrete, glass reinforced plastic polywood

60

14. What are the different types of composites?

Particle reinforced

Fibre reinfoeced

Structural

15.What is matrix and reinforcement?

The Major element molten metal is matrix.The material which is added to improve the properties is reinforcement.

PART B

1. Explain the two modes of plastic deformation in metals with neat sketches.( Refer Page No 5.7-5.9 in


(a) Critically compare the deformation by slip and twinning (Refer Page No 5.16 in V.Jayakumar/Sydney H Avener)

(b) Derive an empression for critical resolved shear stress in material subjected to uni-axial tensile loading. Also

distinguish between shear strees and critical resolved shear stress.( Refer Page No 5.12-5.14 in V.Jayakumar/Sydney

H Avener)

2. What is brittle fracture? Explain the Griffith‟s theory on brittle fracture and deduce and expression for the critical stress

required to propagate a crack simultaneously in a brittle material.( Refer Page No 5.17-5.20 in V.Jayakumar/Sydney H

Avener)

3. What ia meant by ductile fracture?Explain the mechanism of it. (Refer Page No 5.21-5.23 in V.Jayakumar/Sydney H

Avener)

4. (a)Explain the mechanism of fatigue fracture(Refer Page No5.25 in V.Jayakumar/Sydney H Avener)

(b)Discuss any two mechanisms of creep fracture(Refer Page No5.27-5.31 in V.Jayakumar)

(c)How can you prevent: (i) fatigue fracture, and (ii)creep fracture.( Refer Page No5.27-5.31)

5. (a) Describe a tensile test to determine various tensile properties.( ReferPage No5.33-5.38)

b) Explain the testing procedure of (i) a compression test, and (ii) a shear test.( Refer Page No 5.43 in


61

SUBJECT NAME: STRENGTH OF MATERIALS

UNIT I STRESS, STRAIN AND DEFORMATION OF SOLIDS


1. Define stress

When an external force acts on a body, it undergoes deformation. The internal resistance offered by the material against

deformation is called stress.

2. Define strain

Strain is the ratio of the change in dimension to the orginial dimension.

3. State Hook’s law.

When the material is loaded within its elastic limit,the stress is directly proportional to the strain.

4. Define modulus of rigidity

It is the ratio between shear stress to the corresponding shear strain and is constant within its elasticlimit.

5. What are the types of strain?

a) Tensile stress

b) Bending stress

c)Torsional stress

6. Define simple stress

When a body is subjected to an external force in one direction only, the stress developed in the body.

7. Define Compound stress.

When a body is subjected to an external force in more than one direction ,the stress developed in the body.

8. What are the types of strain?

a) Tensile strain

b) Compressive strain

c) Shear strain

9. Define factor of safety

The ratio of ultimate stress to the working stress is called factor of safety

62

10. Define load factor.

The ratio of ultimate load to the working load is called load factor.

11. Define volumetric strain.

It is defined as the ratio between the change in volume to the orginal volume.

12. State principal plane.

The plane which has no shear stress is known as principal plane.

13. Define principal stresses.

The stresses acting on principal planes are known as principal stresses.

14. Define temperature strain.

The strain in the body due to the change in temperature is known as temperature strain.

15. Define temperature stress.

The stresses in the body due to the change in temperature is known as temperature stress

16. What are the types of elastic constants?

a) The modulus of elasticity

b) Bulk modulus

c) Modulus of rigidity

17. Define creep.

The slow and progressive deformation of a material with time at constant stress is called as creep.

18. Define strength

The ability of a material to resist the externally applied forces without breaking is known as strength

19. Define stiffness

It is the property of a material to resist elastic deformation

20. Define Elasticity.

The property of a material to regain its original shape after deformation when the applied force is removed.

21. Define Plasticity

The property of a material which enables the formation of permanent deformation without rupture due to applied load.

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22. What is stability?

It is defined as an ability of a material to withstand high load without major deformation.

PART B

1) A hollow steel tube with an inside diameter of 100mm must carry a tensile load of 400KN. Determine the outside

diameter of the tube of the stress is limited to 120MN/m².

2) A rod is composed of an aluminium section rigidily attached b/w steel and bronze sections.a) Axial loads are vapplied

at the positions indicated.If P=13620N and the cross-sectional area of the rod is 322.58 mm²,determine the stress in

each section.

3) Find the smallest diameter bolt that can be used in the device if P=400KN.The shearing strength for the bolt is 300

Mpa.

4) Assume that a 20mm diameter rivet joint the plates that are each 110 mm wide.The allowable stress are 120 Mpa for

bearing in the plate material and 60 Mpa for shearing of the rivet.Determine a) the minimum thickness of each plate,

b)the largest tangible stress in the plates.

5) At what angular velocity will the stress in a rotating steel ring 150 Mpa if its mean radius is 220mm.The density of steel

is 7.85 Mg/m³.

6) A solid cylinder of steel is placed inside a copper tube. The assembly is compressed b/w rigid plates by forces P. Find

the value of increase in temperature so that all the load is carried by the copper tube.

7) A steel rod having a cross-sectional area of 300 mm²and a length of 150 m is suspended vertically from one end. It

supports a tensile load of 20 kN of the lower end. If the unit mass of steel is 7850 kg/m³and E=200X10³ Mn/m², find

the total elongation of the rod.

8) A round bar of length L, which tapers uniformly from Diameter d2 at one end to a smaller diameter. d1 at the other is

suspended vertically from the large end. If W is the weight per unit volume, find the elongation of the rod curved by its

own weight.

9) A reinforced concrete column 200 mm in diameter is designed to carry an axial compressive load of 300 kN .

Determine the required area of the reinforcing steel of the allowable stresses are 6 MPa and 120 MPa for the concrete

and steel, respectively. Use Eco =140 GPa and Est = 200 GPa.

10) A rigid block of mass M is supported by three symmetrically spaced rods as shown. Each copper rod has an areaof

900 mm²; E=120 GPa and the allowable stress is 70 MPa. The steel rod has an area of 1200 mm²; E=200 GPa ; and

the allowable stress is 140 MPa . Determine the largest mass on which can be supported.

64

UNIT -2: BEAMS-LOADS AND STRESSES


1. What is beam?

A beam is a structural member which is subjected to a system of external forces acting perpendicular to

the axis.

2. Define shear force.

Shear force at a cross section of a beam may be defined as unbalanced vertical force to the right or left of

the section.

3. What is cantilever beam?

A beam with one end free and the other end fixed is called cantilever beam.

4. What is simply supported beam?

If the ends of the beam are made to rest freely on supports,the beam is called freely or simply supported beam.

5. What is overhanging beam?

If the length of the beam is extended beyond the end supports in a simply supported beam, then it is called

overhanging beam.

6. What is point load?

A load which is acting at a point is called point load.

7.What is UDL?

If a load which is spread over a beam in such a manner that the rate of loading „W‟ Is uniform through out the

length, then it is called as UDL.

8. Define maximum bending moment.

Bending moment will be maximum when the shear force changes its sign.

9. What are the different types of loads that are acting on the beam?

a) Point load

b) Uniformly distributed load

c) Uniformly Varying load

10. Define the term the point of contra flexture.

The point where the bending moment changes its sign is called the point of contra flexture.

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11. What is the nature of curve by the beam carrying UDL?

The curve follows parabolic curve.

12. Define section modulus.

It is the ratio of moment of inertia of the section to the distance of the plane from neutral axis.

13. Define modular ratio.

The strain at the common surface of a composite beam is same.

14. What is a fitched beam?

A beam which is constructed by two different materials is called fitched beam.

15. Define shear stress distribution?

The variation of shear stress along the depth of the beam is called shear stress distribution.

16. What types of stresses are caused in a beam subjected to a constant shear force?

a) Vertical shear stress

b)Horizontal shear stress.

17. What do you mean by simple bending?

If a beam is bent only due to application of constant bending moment and not due to shear force it

is called simple bending.

PART B

1) A cantilever beam, 50mm wide by 150 mm high and 6 m long, carries a load that varies uniformly from zero at the end

to 1000 N/m at the wall. (a) Compute the magnitude and location of the maximum flexural stress. (b) Determine the

type and magnitude of the stress in a fibre 20 mm from the top of the beam at a section 2m from the free end.

2) A high-strength steel band saw, 20 mm wide by 0.80 mm thick is developed ? What minimum diameter pulleys can be

used without exceeding a flexural stress of 400 MPa ? Assume E = 200 GPa.

3) A 50-mm diameter bar is used as a simply supported beam 3 m long. Determine the largest uniformly distributed load

that can be applied over the right tw0-thirds of the beam if the flexural stress is limited to 50 MPa.

4) A rectangular steel bar, 15mm wide by 30 mm high and 6 m long, is simply supported is its ends. If the density of steel

is 7850 kg/m³, determine the maximum bending stress caused by the weight of the bar.

5) Compare the flexural strength of the following three beams of equal weight.

(i) I- section 100 mmx 200 mm having 10 mm flange thickness and 8 mm thickness. (ii) A rectangular section

having depth equal to twice the width (iii) Solid circular section.

66

6) A solid rod of bronze 20 mm in diameter is surrounded by a fitting steel cylinder of external diameter 28 mm . If the

permissible b en ding stress in bronze and steel are 100 and 150 N/mm²,find the moment of resistance of the

composite section. The young‟s modulus for steel may be taken as 1.75 times that of bronze.

7) A timber beam 80mm wide by 160mm high is subjected to a vertical shear v=40 KN.Determine the shearing stress

developed at layers 20mm apart from top to bottom to the section.

8) A 50mm diameter bar is used as a simply supported beam 3m long.Determine the largest uniformly disturbuted load

that can be applied over the right two-thirds of the beam, if the flexural stress is limited to 50Mpa.

9) A rectangular steel bar,15mm wide by 30mm high and 6m long, is simply supported at its ends.If the density of the

steel is 7850 Kg/m³, determine the maximum bending stress caused by the weight of the bar.

10) Compare the flexural strength of the following three beams of equal weight

I) I-section 100mm*200mm having 10mm flange thickness and 8mm thickness.

ii) A rectangular section having depth equal to twice the width

iii) Solid circular section.

UNIT-3


1. Define torsion.

When a pair of forces of equal magnitude but opposite directions act on the body, it tends to

twist the body.

2. State the assumptions made in theory of pure torsion.

a) The material of the shaft is uniform throughout.

b)The twist along the shaft is uniform.

c)The shaft is of uniform circular section throughout.

3. Define polar modulus.

Polar modulus is the ratio between the polar moment of inertia of the shaft section to the

maximum radius.

4. What is stepped shaft?

Sometimes a shaft, made up of different lengths having different cross sectional areas is

required to transmit some torque from one pulley to another.

5. What is compound shaft?

A shaft is made of two (or) more different materials and behaving as a single shaft is known as

compound shaft.

6. Name two different types of spring.

a)Bending spring

b) Torsion spring

67

7. What is spring?

It is a device which is used to absorb energy due to resilience,by very large change in its

form without permanent deformation.

8. Define helical spring? Name any two types of helical spring.

It is a torsion spring and made up of a wire coiled into a helix.

Types of helical spring

a)Open coiled helical spring

b)Closed coiled helical spring

9. Define stiffness of spring.

The load required to produce a unit deflection of a spring is called stiffness of spring.

10. What is meant by spring constant.

It is ratio of the mean diameter of the spring to the diameter of the wire.

11. What are the uses of open coiled helical spring.

a) Shock absorbers in automobiles

b) Railway coaches.

12. What are the uses of close coiled helical spring.

a)Brakes

b)Pistals

c)Cycle stand

13 .What kind of stress induced when an axial load acts on a open coiled spring?

The stresses induced are,

a) Bending stress

b) Shear stress

14. What kind of stress induced when an axial load acts on a close Coiled spring?

Shear stress is induced.

PART B

1) Whatis the minimum diameter of a solid steel shaft that will not twist through more than 3° in a 6m length when

subjected to a torque of 12KN-m?What maximum shearing stress is developed? Use G=83Gpa.

2) A solid shaft 5 m long is stressed to 80Mpa when twisted through 4°.Using G=83 Gpa,copute the shaft diameter. What

power can be transmitted by the shaft at 20 HZ?

3) Show that a hollow circular shaft whose inner diameter is half the outer diameter has a torsional strength equal to

15/16 of that of a solid shaft of the same outside diameter.

4) Determine the maximum torque that can be applied to a hollow circular steel shaft of 100mm outside diameter and an

80mm inside diameter without exceeding a shering stress of 60Mpa or a twist of 0.5 deg/m. Use G=83 Gpa.

5) A flanged bolt coupling consists of ten steel 20mm diameter bolts spaced evenly around a bolt circle 400mm in

diameter. Determine the torque capacity of the coupling if the allowable shearing stress in the bolts is 40 Mpa.

6) Compute the maximum shearing stress developed in a phosphor bronze spring having a mean diameter of 200 mm

and consisting of 24 turns of 20mm diameter wire when the spring is stretched 100mm and G=42 Gpa.

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7) Determine the maximum shearing stress and elongation in a helical steel spring composed of 20 turns of 20mm

diameter wire on a mean radius of 90mm when the spring is supporting a load of 1.5KN. and G=83 Gpa.

8) A solid shaft of 250mm diameter has the same cross sectional area as the hollow shaft of the same material with inside

diameter of 200mm a) Find the ratio of power trans mitted by the two shafts for the same angular velocity and b)

compare the angles of twist in equal lengths of these shafts, when stressed to the same intensity.

9) A close-coiled helical spring has to absorb 60N.m of energy when compressed 60mm. The coil diameter is eight times

the wire diameter. If there are ten coils, determine a)diameter of the coil, b)diameter of the wire, c) the maximum shear

stress .Take N=0.86*10^5 N/mm².

10) A open coiled helical spring , made out of 20mm diameter steel rod,has 10 complete turns at a mean diameter of

150mm,the angle of helix being 15°. An axial load of 400N is applied. Compute a)Deflection under the load andb)

maximum intensities of direct and shear stresses ,induced in the section of the wire. Take N=0.84*10^5N/mm² and

E=2*10^5 N/mm².

Unit-4: BEAM DEFLECTION


1. Define neutral plane

The layer EF which is neither compressed nor stretched is known as neural plane.

2. Define neutral axis.

The line of intersection of the neutral layer with any normal cross section of a beam is known as neutral axis.

3. Define slope.

The angle made by the tangent at a point on the elastic curve with the horizontal is called the slope at the point.

4. Define deflection.

It is measured by the distance through which elastic line has moved vertically due applied load with respect to the

undeflected centre line of beam.

5 .Define flexural rigidity.

The product EI is called the flexural rigidity.

6. What are the units of slope and deflection?

Unit of slope is radians.

Unit of deflection is metre .

7. Define elastic curve.

The line to which the longitudinal axis of a beam bends is known as elastic curve.

8. What are the methods used to find the values of slope and deflection at a section of a beam?

69

The methods used are,

a)Moment area method

b)Macaulay‟s method

c)Macauly‟s method

d)Conjucate beam method

9. Where the maximum deflection will occur in a SSB loaded with UDL of ‘W’ kN/m run?

Maximum deflection will occur at the centre of the beam at which the slope is zero.

10) State Macaulay’s method?

In Macaulay‟s method,a continuous expression is integrated in such a way that the constants of integration are valid

for all sections,eventhough the law of bending moment varies from section to section.

11) Define column (or) strut.

Column (or) strut is defined as a member of a structure , which is subjected to axial compressive load.

Strut may be horizontal, inclined (or) even vertical.,

Vertical strut used in buildings (or) frames is called a column.

12) What are the failures of the column?

Failure of a column takes place due to the any one of the following stresses.

a) Direct compressive stress

b) Buckling stress

c) Combined direct compressive and buckling stresses.

13) What are the types of end conditions of column?

The column has the following end conditions.

a) Both ends hinged

b) Both ends fixed

c) One end is fixed and the other hinged

d) One end is fixed and the other free.

14) What are assumptions made in the Euler’s column theory?

In Euler‟s column theory, the following assumptions are made.

a) Initially the column is perfectly straight and the load applied is truly axial.

b) The cross section of the column is uniform throughout its length.

70

15) Define slenderness ratio.

The ratio of the actual length of a column to the least radius of gyration of the column is known as

slenderness ratio.

16) What is the limitation of Euler’s formula?

If the slenderness ration is less than 80 for mild steel column with both ends hinged, the Euler‟s

formula will not be valid.

17) What is the equivalent length of a column?

The equivalent length of a given column with given end conditions is the length of an equivalent

column of the same material and cross section with hinged ends, and having the value of the

crippling load equal to that of the given column.

18) Write down the expression for Euler’s crippling load for a long column when both ends hinged.

Euler‟s crippling load for a long column when both ends hinged is,

P= EI/

19) State the theorems in the moment area method.

Mohr‟s theorem 1

The Change of slope between any two points is equal to the net area of the BM

diagram between these points divided by EI.

Mohr‟s theorem 2

The total deflection between any two points is equal to the moment of the area of

the BM diagram between these two points about the last point divided by EI.

20) Slenderness ratio is more than 80 and less than 80 is called what type of column

More than 80 is called as long columns, less than 80 is called as short column.

PART B:

1) Determine the maximum deflection δ in a simply supported beam of length L varying a concentrated load P at a

midspan.

2) Determine the maximum deflection δ in a simply supported beam of length L carrying a uniformly disturbed load

intensity w0 applied over its entire length.

3) A cantilever is acted on by a uniformly distributed moment of intensity m per unit distance along the axis of the

beam.Find the slope and deflection at the free end.

4) Abeam ACB, simply supported at the ends, has moment of inertia 4I for the length AC and I for the length CB, and is

loaded with point load W at C.Determine (i) Slope at end A, (ii) Deflection at mid-span (iii) Maximum deflection.

5) Calculate the slope at the ends and deflection at the centre of a beam loaded with a couple µ at the centre.

71

6) A cantilever of uniform section has a length AB= L.End B is free end and carries a point load W,while end A is fixed

end. Find the slope and deflection at a point C, distant L/4 from the free end A.

7) A uniform beam of length L is simply and symmetrically over of span L.Find the ratio L/l so that the upward deflection at

each and equals the downward deflection at the mid-span due to a central point load.

8) A simply supported beam of span 8m carries a point load of 20KN at a distance of 6m from the left end. Compute (a)

the slope at the left end (b) the deflection under the load (c) the deflection at the mid-span and (d) the maximum

deflection and its location Take E=2*10^5N/mm² and I=6*10^8 mm³.

9) A freely supported beam of span L carries a central load W. The sectional area of the beam is so designed that the

moment of inertia of section increases uniformly from 1 at the ends to1.51 at the middle. Calculate the central

deflection.

UNIT-5 ANALYSIS OF STRESSES IN TWO DIMENSIONS


1. Define thin cylinder and thick cylinder.

When the ratio of wall thickness to the diameter of cylinder is less than 1/20, the cylinder is called as a thin cylinder.

When the ratio of wall thickness to the diameter of cylinder is more than 1/20,the cylinder is called as a thick cylinder.

2. Define hoop stress.

The stress acting along the circumference of the cylinder is called circumferential stress.

3. Define longitudinal stress.

The stress acting along the length of the cylinder is known as longitudinal stress.

4. Write the expression for longitudinal stress in thin cylinder due to internal pressure ‘p’.

In the thin cylinder,

Longitudinal stress=pd/4t.

5. Write the expression for hoop stress in thin cylinder due to internal pressure’p’.

Hoop stress=pd/2t.

6 . Define principal stress.

The stresses acting on the principal planes are known as principal stress.

7. Define principal plane.

The planes which have no shear stress are known as principal plane.

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8. Define the term obliquity.

The angle made by the resultant stress with the normal of the oblique plane is known as obliquity.

9. What is the radius of mohr’s circle?

Radius of mohr‟s circle is equal to the maximum shear stress.

10. What is the use of Mohr’s circle?

It is used to find out the normal,tangential,resultant stresses and principal stress and their plane.

11. In case of equal like principal stresses, what is the diameter of the Mohr’s circle?

The diameter is zero.

12. Define strain energy.

Whenever a body is strained,some amount of energy is observed in the body.The energy which is observed in the

body due to straining effect is known as strain energy.

13. What are the planes along which the greatest shear stress occurs?

Greatest shear stress occurs at the planes which is inclined at 45° to its normal.

14. What is effect of riveting a thin cylindrical shell?

It reduces the pressure carrying capacity of the shell.

It reduces the area offering the resistance.

PART – B

1) At a point in a beam the longitudinal tensile stress is 80 MN/m² and the shear stress is 45 MN/m². Find the magnitude

and direction of principal stresses at the point. What is the magnitude and direction of the greatest shear stress?

2) At a point in beam the bending stress is 80 N/mm². The greatest principal stress is to be limited to 90 N/mm². What is

the greatest shearing stress that can be applied on the given planes. Determine the maximum principal stress and

direction.

3) At atmospheric pressure, a thin spherical shell has diameter 750mm and thickness 8 mm. Find the stress introduced

and change in diameter and volume when the fluid pressure is increased to 2.5N/mm².Take E=2*10^5 N/mm²,µ =0.25.

4) A pipe of 400mm internal diameter and 100mm thickness contains a fluid at a pressure 80N/mm².Find the maximum

and minimum hoop stresses across the section. Also sketch the radial and hoop stress distribution across the section.

5) A thick cylindrical pipe outside diameter 300mm and internal diameter 200mm is subjected to an internal fluid pressure

of 14 N/mm².Determine the maximum hoop stress developed in the cross section. Sketch the variation of hoop stress

across the thickness of the pipe.

What is the percentage of error if the maximum hoop stress is found from the equation for thin pipes?

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6) A thick cylinder of internal diameter 160mm is subjected to an internal pressure 40N/mm². If the allowable stress in the

material is 120 N/mm², find the thickness required.

7) A thick spherical shell of 400 mm external diameter and 50mm thick is subjected to internal fluid pressure of 50

N/mm².Draw the variation of hoop stress across the thickness.

8) A compound cylinder of inner radius 100mm,outer radius 240mm has common radius at 180mm. The radial pressure

developed at junction is 12 N/mm².Determine the radial and hoop stresses developed at inner, common and outer radii

when the fluid is admitted at a pressure of 60N/mm².

9) In a chemical plant a sphere of diameter 900mm and metal thickness 8mm is used to stire a gas. If the permissible

stress in the metal is 150 N/mm²,find the maximum pressure with which the gas can be stored if

i) the sphere is seamless

ii) the efficiency of joint is 0.65

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SUBJECT NAME: ELECTRONICS AND MICROPROCESSOR

UNIT I: SEMICONDUCTOR THEORY


1. What are valence electrons?

Electron in the outer most shell of an atom is called valence electron.

2. What is forbidden energy gap?

The space between the valence and conduction band is said to be forbidden energy gap.

3. What are conductors? Give examples?

Conductors are materials in which the valence and conduction band overlap each

other so there is a swift movement of electrons which leads to conduction. Ex. Copper, silver.

4. What are insulators? Give examples?

Insulators are materials in which the valence and conduction band are far away

from each other. So no movement of free electrons and thus no conduction. Ex glass, plastic.

5. What are Semiconductors? Give examples?

The materials whose electrical property lies between those of conductors and

insulators are known as Semiconductors. Ex germanium, silicon.

6. What are the types of Semiconductor?

1. Intrinsic semiconductor 2. Extrinsic semiconductor.

7. What is Intrinsic Semiconductor?

Pure form of semiconductors are said to be intrinsic semiconductor. Ex germanium, silicon.

8. What is Extrinsic Semiconductor?

If certain amount of impurity atom is added to intrinsic semiconductor the resulting semiconductor is Extrinsic or

impure Semiconductor.

9. What are the types of Extrinsic Semiconductor?

1. P-type Semiconductor 2. N- Type Semiconductor.

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10. What is P-type Semiconductor?

The Semiconductor which are obtained by introducing pentavalent impurity atom (phosphorous, antimony) are

known as P-type Semiconductor.

11. What is N-type Semiconductor?

The Semiconductor which are obtained by introducing trivalent impurity atom (gallium, indium) are known as N-type

Semiconductor.

12. What is doping?

Process of adding impurity to an semiconductor atom is doping. The impurity is called dopant.

13. Which is majority and minority carrier in N-type Semiconductor?

Majority carrier: electrons and minority carrier: holes.

14. Which is majority and minority carrier in P-type Semiconductor?

Majority carrier: holes and minority carrier: electrons.

15. What is depletion region in PN junction?

The diffusion of holes and electrons will result in difference in concentration across the junction which in turn

results in the movement of the mobile charge carriers to the junction thus resulting in a region called depletion region.

16. What is barrier voltage?

Because of the oppositely charged ions present on both sides of PN junction an

electric potential is established across the junction even without any external voltage source which is termed as barrier

potential.

17. What is meant by biasing a PN junction?

Connecting a PN junction to an external voltage source is biasing a PN junction.

18. What are the types of biasing a PN junction?

1. Forward bias 2. Reverse bias.

19. What is forward bias and reverse bias in a PN junction?

When positive of the supply is connected to P type and negative to N type then it

is forward bias. When positive of the supply is connected to N type and negative to P type then it is reverse bias.

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20. What is Reverse saturation current?

The current due to the minority carriers in reverse bias is said to be reverse saturation current.

21. What is reverse break down?

During reverse bias after certain reverse voltage the current through the junction increases abruptly thus

breaking the crystal which is termed as reverse break down.

22. Give the diode current equation?

I = I0. (eı__ ____-1)

23. Give two applications of PN junction diode.

1. As rectifier in power supplies.

2. as switch in logic circuits

24. What is rectifier? Give its types.

Rectifier converts A.C to pulsating D.C. Types are HWR and FWR.

Part-B

25. Explain N-type and P-type semiconductor with their energy band diagram?

Definition of extrinsic semiconductor and its types , N-type semiconductor Definition ,Diagram of crystalline

structure and energy band , P-type semiconductor .Definition Diagram of crystalline structure and energy band

26. Explain the following

a. Mobility b. Drift current c. Conductivity d. Diffusion current

a. mobility - definition and relation required b. Drift current – definition, diagrams and derivation of relation

require,c. Conductivity - definition and relation required ,d. Diffusion current - definition, diagrams and derivation of

relation required

27. What is break down in diode? What are its types?

Definition of break down and explanation ,Zener break down Avalanche break down .

Unit II TRANSISTORS

1. What is a transistor (BJT)?

Transistor is a three terminal device whose output current, voltage and /or power is controlled by input current.

2. What are the terminals present in a transistor?

Three terminals: emitter, base, collector.

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3. What is FET?

FET is abbreviated for field effect transistor. It is a three terminal device with its output characteristics

controlled by input voltage.

4. Why FET is called voltage controlled device?

The output characteristics of FET is controlled by its input voltage thus it is voltage controlled.

5. What are the two main types of FET?

1. JFET 2. MOSFET.

6. What are the terminals available in FET?

1. Drain 2. Source 3. Gat

7. What is JFET?

JFET- Junction field effect transistor.

8. What are the types of JFET?

N- channel JFET and P- Channel JFET

9. What are the two important characteristics of JFET?

1. Drain characteristics 2. Transfer characteristics.

10. What is transconductance in JFET?

It is the ratio of small change in drain current to he corresponding change in drain to source voltage.

11. What is amplification factor in JFET?

It is the ratio of small change in drain to source voltage to the corresponding change in Gate to source voltage.

12. Why do we choose q point at the center of the loadline?

The operating point of a transistor is kept fixed usually at the center of the active region in order that the input

signal is well amplified. If the point is fixed in the saturation region or the cut off region the positive and negative half

cycle gets clipped off respectively.

13. List out the different types of biasing. ._

Voltage divider bias ,Base bias,Emitter feed back bias,Collector feedback bias,Emitter bias.

14. What do you meant by thermal runway?

Due to the self heating at the collector junction, the collector current rises. This causes damage to the device.

This phenomenon is called thermal runway.

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15. Why is the transistor called a current controlled device?

The output characteristics of the transistor depend on the input current. So the transistor is called a current

controlled device.

16. Define current amplification factor?

It is defined as the ratio of change in output current to the change in input current at constant.

17. What are the requirements for biasing circuits?

The q point must be taken at the Centre of the active region of the output characteristics.

Stabilize the collector current against the temperature variations.

Make the q point independent of the transistor parameters.

.When the transistor is replaced, it must be of same type.

18. When does a transistor act as a switch?

The transistor acts as a switch when it is operated at either cutoff region or saturation Region

19. What is biasing?

To use the transistor in any application it is necessary to provide sufficient voltage and current to operate the

transistor. This is called biasing.

20. What is stability factor?

Stability factor is defined as the rate of change of collector current with respect to the rate of change of reverse

saturation current.

21. Explain about the various regions in a transistor?

The three regions are active region saturation region cutoff region.

22. Explain about the characteristics of a transistor?

Input characteristics: it is drawn between input voltage & input current while keeping output voltage as

constant.

Output characteristics: It is drawn between the output voltage &output current while keeping input current as

constant.

Part-B

23. Explain the construction, operation, volt ampere characteristics, and application of SCR, also explain its two

transistor model.

Construction ,Equivalent circuit and two transistor model, Operation ,Volt ampere characteristics Application

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24. Explain the construction, operation, equivalent circuit, volt ampere characteristics, and application of UJT.

Construction, Equivalent circuit, Operation ,Volt ampere characteristics, Application

25. Explain the construction, operation, equivalent circuit, volt ampere characteristics, and application of DIAC.

Construction, Equivalent circuit, Operation ,Volt ampere characteristics, Application

26. Explain the construction, operation, equivalent circuit, volt ampere characteristics, and application of TRIAC

Construction, Equivalent circuit, Operation ,Volt ampere characteristics ,Application

Unit III DIGITAL ELECTRONICS


1. Define binary logic?

Binary logic consists of binary variables and logical operations. The variables are designated by the alphabets

such as A, B, C, x, y, z, etc., with each variable having only two distinct values: 1 and 0. There are three basic logic

operations: AND, OR, and NOT.

2. Convert (634) 8 to binary

634 = 110 011 100

Ans = 110011100

3. Convert 0.640625 decimal number to its octal equivalent.

0.640625 x 8 = 5.125

0.125 x 8 = 1.0

0.640 625 10 = (0.51) 8

4. Convert 0.1289062 decimal number to its hex equivalent

0.1289062 x 16 = 2.0625

0.0625 x 16 = 1.0

0.1289062 = (0.21) 16

5. Subtract (0 1 0 1) 2 from (1 0 1 1) 2

1 0 1 0

0 1 0 1

Answer = 0 1 1 0

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6. Add (1 0 1 0) 2 and (0 0 1 1) 2

1 0 1 0

0 0 1 1

Answer = (1 1 0 1) 2

7. Using 10’s complement subtract 72532 - 3250

M = 72532

10‟s complement of N = + 96750

Sum = 169282

Discard end carry

Answer = 69282

8. Find 2’S complement of (1 0 1 0 0 0 1 1) 2

0 1 0 1 1 1 0 0 1 - 1‟s Complement + 1

0 1 0 1 1 1 0 1 0 - 2‟s complement.

9. Subtract 1 1 1 0 0 1 2 from 1 0 1 0 1 1 2 using 2’ s complement method

1 0 1 0 1 1

+ 0 0 0 1 1 1 - 2‟ s comp. of 1 1 1 0 0 1

_________

1 1 0 0 1 0

Answer in 2‟ s complement form (0 0 1 1 1 0 )2

10. What is meant by bit?

A binary digit is called bit

11. Define byte?

Group of 8 bits.

12. List the different number systems?

i) Decimal Number system

ii) Binary Number system

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iii) Octal Number system

iv) Hexadecimal Number system

13. What are the different types of number complements?

i) r‟ s Complement

ii) (r-1)‟ s Complement.

14. Given the two binary numbers X = 1010100 and Y = 1000011, perform the

subtraction (a) X -Y and (b) Y - X using 2’s complements.

a) X = 1010100

2‟s complement of Y = 0111101

--------------

Sum = 10010001

Discard end carry

Answer: X - Y = 0010001

b) Y = 1000011

2‟s complement of X = + 0101100

---------------

Sum = 1101111

There is no end carry, The MSB BIT IS 1.

Answer is Y-X = -(2‟s complement of 1101111) = - 0010001

15. Write the names of basic logical operators.

1. NOT / INVERT

2. AND

3. OR

16. What are basic properties of Boolean algebra?

The basic properties of Boolean algebra are commutative property, associative

property and distributive property.

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17. State the associative property of boolean algebra.

The associative property of Boolean algebra states that the OR ing of several variables results in the same

regardless of the grouping of the variables. The associative property is stated as follows: A+ (B+C) = (A+B) +C

18. State the commutative property of Boolean algebra.

The commutative property states that the order in which the variables are OR ed makes no difference. The

commutative property is: A+B=B+A

19. State the distributive property of Boolean algebra.

The distributive property states that AND ing several variables and OR ing the result with a single variable is

equivalent to OR ing the single variable with each of the the several variables and then AND ing the sums. The

distributive property is: A+BC= (A+B) (A+C)

20. What are the classification of sequential circuits?

The sequential circuits are classified on the basis of timing of their signals into two types. They are,

1)Synchronous sequential circuit.

2)Asynchronous sequential circuit

21. Define Flipflop.

The basic unit for storage is flipflop.A flip-flop maintains its output state either at 1 or 0 until directed by an

input signal to change its state.

22. What are the different types of flip-flop?

There are various types of flipflop.Some of them are mentioned below they are,

i)RS flip-flop

ii) D flip-flop

iii)JK flip-flop

iv)T flip-flop

Part-B

23. What is the operation of RS flip-flop?

When R input is low and S input is high the Q output of flip-flop is set.

When R input is high and S input is low the Q output of flip-flop is reset.

When both the inputs R and S are low the output does not change

When both the inputs R and S are high the output is unpredictable.

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24. What is the operation of SR flip-flop?

When R input is low and S input is high the Q output of flip-flop is set.

When R input is high and S input is low the Q output of flip-flop is reset.

When both the inputs R and S are low the output does not change.

When both the inputs R and S are high the output is unpredictable.

25. What is the operation of D flip-flop?

In D flip-flop during the occurrence of clock pulse if D=1, the output Q is set and if D=0, the output is reset.

26. What is the operation of JK flip-flop?

When K input is low and J input is high the Q output of flip-flop is set.

When K input is high and J input is low the Q output of flip-flop is reset.

When both the inputs K and J are low the output does not change

When both the inputs K and J are high it is possible to set or reset

28. What is the operation of T flip-flop?

T flip-flop is also known as Toggle flip-flop.

When T=0 there is no change in the output.

When T=1 the output switch to the complement state (ie) the output toggles.

29. What are the different types of shift type?

There are five types. They are, ._Serial In Serial Out Shift Register ._Serial In Parallel

Out Shift Register ._Parallel In Serial Out Shift Register ._Parallel In Parallel Out Shift Register ._Bidirectional

Shift Register

30. Explain counters.

Synchronous counters, These counters use common clock pulse. It may be a up counter or down counter. It

uses JK flip flop. ,Asynchronous counters There is no common clock pulse. The output of each flip flop is the clock

pulse for next flip flop. It uses JK or T flip flop.

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Unit IV 8085 MICROPROCESSOR


1. Give What is microprocessor. the power supply & clock frequency of 8085

A microprocessor is a multipurpose, programmable logic device that reads binary instructions from a storage

device called memory, accepts binary data as input and processes data according to those instructions and provide

result as output. The power supply of 8085 is +5V and clock frequency in 3MHz.

2. What is the signal classification of 8085

All the signals of 8085 can be classified into 6 groups

Address bus ,Data bus ,Control and status signals

Power supply and frequency signals ,Externally initiated signals &

Serial I/O ports

3. What are operations performed on data in 8085

The various operations performed are

Store 8-bit data

Perform arithmetic and logical operations

Test for conditions

Sequence the execution of instructions

Store data temporarily during execution in the defined R/W memory locations called the stack

4. Steps involved to fetch a byte in 8085

The PC places the 16-bit memory address on the address bus

The control unit sends the control signal RD to enable the memory chip

The byte from the memory location is placed on the data bus

The byte is placed in the instruction decoder of the microprocessor and the task is carried out according to the

instruction

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5. How many interrupts does 8085 have, mention them

The 8085 has 5 interrupt signals, they are INTR, RST7.5, RST6.5, RST5.5 and TRAP

6. Basic concepts in memory interfacing

The primary function of memory interfacing is that the microprocessor should be able to read from and write

into a given register of a memory chip. To perform these operations the microprocessor should

Be able to select the chip

Identify the register

Enable the appropriate buffer

7. Define instruction cycle, machine cycle and T-state

Instruction cycle is defined as the time required to complete the execution of an instruction. Machine cycle is

defined as the time required to complete one operation of accessing memory, I/O or acknowledging an external

request. T-cycle is defined as one subdivision of the operation performed in one clock period

8. What is an instruction?

An instruction is a binary pattern entered through an input device to command the microprocessor to perform that specific

function

9. What is the use of ALE

The ALE is used to latch the lower order address so that it can be available in T2 and T3 and used for

identifying the memory address. During T1 the ALE goes high, the latch is transparent ie, the output changes

according to the input data, so the output of the latch is the lower order address. When ALE goes low the lower order

address is latched until the next ALE.

10. How many machine cycles does 8085 have, mention them

The 8085 has seven machine cycles. They are Opcode fetch , Memory read ,Memory write ,I/O read ,I/O write

,Interrupt acknowledge , Bus idle

11. Explain the signals HOLD, READY and SID

HOLD indicates that a peripheral such as DMA controller is requesting the use of address bus, data bus and

control bus.

READY is used to delay the microprocessor read or write cycles until a slow responding peripheral is ready to

send or accept data.

SID is used to accept serial data bit by bit

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12. Mention the categories of instruction and give two examples for each category

The instructions of 8085 can be categorized into the following five

Data transfer MOV Rd,Rs STA 16-bit

Arithmetic ADD R DCR M

Logical XRI 8-bit RAR

Branching JNZ CALL 16-bit

Machine control HLT NOP

13. Explain LDA, STA and DAA instructions

LDA copies the data byte into accumulator from the memory location specified by the 16-bit address. STA

copies the data byte from the accumulator in the memory location specified by 16-bit address. DAA changes the

contents of the accumulator from binary to 4-bit BCD digits.

14. Explain the different instruction formats with examples

The instruction set is grouped into the following formats

One byte instruction MOV C,A

Two byte instruction MVI A,39H

Three byte instruction JMP 2345H

15. What is the use of addressing modes , mention the different types

The various formats of specifying the operands are called addressing modes, it is used

to access the operands or data. The different types are as follows

Immediate addressing

Register addressing

Direct addressing

Indirect addressing

Implicit addressing

16. Differentiate between absolute and linear select decoding?

Absolute decoding All higher address lines are defined to select the memory or I/O device

Linear decoding Few higher address lines are decoded to select the memory or I/O device

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17. What is the use of bi-directional buffers

It is used to increase the driving capacity of the data bus. The data bus of a microcomputer system is bi-directional, so it

requires a buffer that allows the data to flow in both directions.

18. Give the resister organization of 8085

B,C,D,E,H,L,Z,W

19. Define stack and explain stack related instructions

The stack is a group of memory locations in the R/W memory that is used for the temporary storage of binary

information during the execution of the program. The stack related instructions are PUSH & POP

20. Why do we use XRA A instruction?

The XRA A instruction is used to clear the contents of the Accumulator and store the value 00H.

21. Define PSW

The PSW or flags are used to reflect the data conditions in the accumulator. The 8085 flags are S-Sign flag, Z-

Zero flag, AC-Auxiliary carry flag, P-Parity flag, CY-Carry flag.

22. What is Microcontroller and Microcomputer

Microcontroller is a device that includes microprocessor, memory and I/O signal lines On a single chip,

fabricated using VLSI technology. Microcomputer is a computer that Is designed using microprocessor as its CPU. It

includes microprocessor, memory and I/O.

Part-B

23. Compare CALL and PUSH instructions

CALL PUSH When CALL is executed the PUSH to save the contents of the register microprocessor

automatically stores the 16-bit address of the instruction next to CALL on the stack When CALL is executed the stack

pointer When PUSH is executed the stack I is decremented by two. pointer register is decremented by two.

24. How does the microprocessor differentiate between data and instruction.

When the first m/c code of an instruction is fetched and decoded in the instruction register , the microprocessor

recognizes the number of bytes required to fetch the entire instruction. For example MVI A, Data, the second byte is

always considered as data. If the data byte is omitted by mistake whatever is in that memory location will be

considered as data & the byte after the “data” will be treated as the next instruction.

25. Explain 8085 architecture.

_ It is a program controlled device.

_ It fetches, decodes and executes the instructions.

_ It is a 8 bit processor. Since it has a 8 bit data bus.

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_ The ALU has 8 bits. All the registers are 8 bit registers.

_ The address bus has 16 bits. The memory capacity is 64K bytes.

_ It has a 8 bit flag register.

_ The timing and control unit coordinates all the operations.

_ The ALU performs all the arithmetic and logical operations.

_ The address bus carries the address of memory location. The datas are carried by data bus and will be

decoded and executed.

26. Explain the instruction set.

Arithmetic instructions

a)ADD ,b)SUB ,c)INR, d)DCR, e)ADI, f)SUI

Logical instructions

a)ANA , b)ANI ,c)ORA ,d)ORI ,e)XRA ,f)XRI ,g)RAL ,h)RLC ,i)RAR j)RRC

Data transfer instructions

a)MOV ,b)MVI ,c)PUSH ,d)POP ,e)LXI ,f)STA ,g)LDA ,h)LDAX ,i)STAX

Branching instructions

a)JUMP ,b)CALL ,c)RET ,

Machine control instructions

a)STC ,b)CLC, ,c)HLT ,d)NOP

27. Explain the Addressing modes

Register addressing mode MOV A,B , Direct addressing mode STA addr

Indirect addressing mode LDAX Rp , _ Implied addressing mode STC

Immediate addressing mode MVI A,08H

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Unit V INTERFACING APPLICATIONS


1. Give few applications of 8085 microprocessor.

a) Used to measure and control temperature.

b) Used to control stepper motor.

c) Used to control traffic light system

d) Used to control speed of DC motor.

2. List the advantages of microprocessor based system design.

a) It simplifies system design.

b) It reduces size and cost

c) It is flexible in operation

3. What is a Buffer?

It is storage device. It can store a bit. It has one input and output.

4. What is a tristate buffer?

It is a buffer, which has one input line, one output line and an enable line. When enable line is low it acts as a

buffer, otherwise it acts as a high impedance state.

5. What is meant by memory address space?

Memory address space is the maximum possible memory size which can be used in a microprocessor.

6. If an information flows from memory to microprocessor, which signal is used by it?

__

RD

7. What is the use CS pin of a memory chip?

A chip select is used to enable the memory chip.

8. If the starting address of 6K memory is 0D00, then ending address will be

24FF H

9. If an information flows to memory, which signal is used by it?

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WR

10. What is memory mapping?

The assignment of memory addresses to various registers in a memory chip is called memory mapping.

11. What is I/O mapping?

The assignment of addresses to various I/O devices in a memory chip is called I/O mapping.

12. What is memory mapped I/O?

The microprocessor assigns 19 bit address to I/O device. The memory map is shared between memory and

I/O.

13. What is I/O mapped I/O?

The I/O devices have separate addresses. The microprocessor assigns 8 bit address to I/O devices.

14. Mention the advantages of memory mapped I/O.

Arithmetic or logical operations can be directly performed directly with I/O data.

15. Mention the advantages of I/O mapped I/O.

Whole address space is available for memory device and less hardware is required.

16. Mention the disadvantages of I/O mapped I/O.

Arithmetic and logical operation cannot be directly used with I/O data.

17. What is the use of ALE signal?

It is used to de multiplex address and data bus.

18. What is the purpose IO/M signal?

It is used to differentiate memory and IO operations. When 1 means IO operation, 0 means memory

operation.

19. Name the two classifications of stepper motor.

Permanent magnet type and variable reluctant type.

20. List the applications of stepper motor.

Used in printers, robot alarms, X-Y plotter.

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Part-B

21. Explain I/O interfacing.

Input interfacing ,Key boards can be used. ,It uses IN instruction ,3-to-8 decoder is used to decode the

address. ,Output interfacing ,LEDs are used ,Uses OUT instruction 3-to-8 decoder is used to decode the address.

22. Explain stepper motor interfacing.

1. Initialise PPI port A as output port.

2. Store switching sequence in memory.

3. Set the counter.

4. Send first data to stepper motor through port A.

5. Call delay.

6. Repeat 4 to 5 till the count is 0.

7. Repeat 2 to 6 fot continous rotation.

23. Explain traffic light control.

1. initialize all ports oi 8255 as output port.

2. store the sequence in memory.

3. Set the counter.

4. Send first data to port A, second to port B, third to port C.

5. Call delay.

6. Repeat 2 to 6 for continuous control.

24. Explain temperature control using 8085.

1. Initialize 8255 ports.

2. Send SOC to A/D converter.

3. Check EOC from A/D converter.

4. Read data from A/D converter.

5. Store the temperature in memory.

6. Compare the output of A/D converter with desired value.

7. Display the temperature.

IV Mech Qb Eited

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