MODEL QUESTION PAPER

FOUR YEAR B.TECH DEGREE END EXAMINATION

THIRD SEMESTER EXAMINATION

ELECTRICAL & ELECTRONICS ENGINEERING

ELECTRICAL CIRCUITS (EC)

(SCHEME-2013)

Time: 3 Hours Max.Marks:70

Note: 1) Question No. 1 is compulsory & it must be answered first in sequence

at one place only

2) Answer any four from the remaining questions.

1. Answer the following: 10 × 1 = 10M a) Define tree and co-tree

b) Define mutual inductance

c) Draw the locus diagram for RC series circuit

d) Write the relation between line and phase quantities of a star connected system

e) Define resonant frequency and band width

f) State Tellegens theorem

g) Express h11 and h21 in terms of Z parameters

h) Find the response of the circuit shown if the switch is closed at t=0sec.

i) Find the laplace transform of function f(t) = te

-at

j) What will be the approximate voltage across the inductor 100ns after the switch is closed.

2 a) Find the equivalent resistance of the circuit shown and find the current produced by 10V

source (7M)

b) Write the tieset schedule for the circuit shown below develop the equilibrium equations.

(8M)

3 a) Briefly explain the concept of duality with an example (6M)

P.T.O

b) For the network shown in figure find the current flowing through the load resistance (9M)

4 a) If Z1 = 20 -300, Z2 = 40 80

0 and Z3 = 10 +90

0 are the impedances connected in the

form of delta and the supply voltage is 440v. Assume the RYB sequence and so find the

phase currents, line currents and the total power absorbed. (7M)

b) Derive the relation between the line and phase quantities of the star connected system with

neat phasor diagram. (8M)

5 a) Derive the expression for the bandwidth of a series RLC circuit. (7M)

b) Calculate the current through the 3Ωresistor in the circuit shown in figure shown using

superposition theorem. Also calculate the power across the 3Ω resistor. (8M)

6 a) Find the Z parameters of the two port network shown (7M)

b) Obtain the hybrid parameters of the network shown (8M)

7 a) The circuit shown in figure consists of resistance, inductance, and capacitance in series

with a 200 V constant source. When the switch is closed at t = 0. Find the transient current.

(7M)

b) In the circuit shown in figure the switch is moved from 1 to 2 at time t = 0. The steady-

state current having previously established in the R-L circuit, find the expression for the

current i(t) after switching using laplace transform method. (8M)