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CONFIDENTIAL

EH/APR 2006/ENG012

UNIVERSITI

TEKNOLOGI

MARA

FINAL EXAMINATION

COURSE

COURSE

CODE

EXAMINATION

TIME

ENGINEERING PHYSICS

II

ENG012

APRIL 2006

3

HOURS

INSTRUCTIONS TO CAND IDATES

1.

This question paper consists

of SIX (6)

questions.

2. AnswerFOUR

4)

questions only. Start each answ er

on a newpage.

3.

Do not bring anymaterial into theexamination room unless

permission

is given by the

invigilator.

4.

Please check to make sure that this examination pack consists of:

i) the Question Paper

ii)

aone-page Appendix 1 -Listo fConstants

iii)

anAnsw er Booklet- providedby he Faculty

DO NOTTURN T ISP GEUNTILYOU RE

TOLD

TO DO SO

Th is

examination paperconsists of 7 pr inted page s

Hak C ipta

Universiti

TeknologiMARA

CONFIDENTIAL


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CONFIDENTIAL EH APR

2006 ENG012

QUESTION

1

a) An alpha

particle

(charge = +2.0e) is sent at

high speed toward

a

gold nucleus

(charge

=

+79e). What

is the

electrical

force acting on the

alpha particle

when it is

2.0 x 10~

14

m fromthe

gold nucleus?

(4

marks)

b) An ionaccelerated throughapotential difference of 115 Vexperiences an

increase

in kinetic

energy of

7.37*

10 J. Calculate the

charge

on the ion.

(4

m arks)

c)

Find

theequivalent

capacitance

betweenpoints a and b for thegroup ofcapacitors

connected asshownin

Figure

1 ifd=5.00

uF, C

2

=

10.0 uF,

and

C

3

=

2.00

uF.

c,

~

C

2

I I

c.

~ ~ l

;Cs

c

2

I I

1

C

2

FIGURE 1

(8marks)

d) Positive cha rges aresituated at

three

corners of a

rectangle,

as shown inFigure2.

Find

theelectric fieldat the

fourth

cornerat

point

A .

6.00 nC

0.200m

0.600m

3.00nC 5.00nC

FIGURE 2

(9 marks)

H ak

Cipta Universiti Teknologi MARA

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EH APR 2006 ENG012

QUESTION 2

a)

Apointchargeof

+5.00

uC is locatedat thecenter of asphere witharadius of12.0

cm .

Determine

the

electric

flux through

the

surface

of the

sphere.

(4 marks)

b) A potential difference of 12 V is found to produce acurrent of

0.40

A in a 3.2-m

length

of

wire with

a uniform radius of

0.40

cm .

What

is the

resistance

of the

wire

an d

theresistivityof the wire?

(4 marks)

c) What

is the

required resistance

of an

immersion heater

that

will increase

the

temperatureof 1.50 kg of water from10.0C to50.0C in 10.0

min

while

operating

at

120V?

(8

marks)

d) The amm etershowninFigure 3 reads 2 .00 A.Find /i, /

2

,and e.

15.0V

\

I

7.00ft

vw-

5.00ft

W\r-

2.00ft

wv -

FIGURE

3

(9

marks)

QUESTION3

a)

A flat

surface

having an area of 3.2 m

2

is

rotated

in a uniform electric field of

magnitude E =6.2 x

10

5

N/C. Determine theelectric flux through

this

area

(i) wh en the

electric field

is

perpendicular

to the

surface

and

(ii)

when

the

electric field

is

parallel

to the

surface.

(4

marks)

b) The half-lifeo f

131

I

is8.04days.

(i) Ca lculate the

decay

constant forthis

isotope.

(ii)

Find

the number of

131

I nucleinecessary to

produce

a

sample with

anactivity

of

0.50

juCi.

(4 m arks)

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c) Tw oparallel plates,

each

of

area 2.00

cm

2

, areseparated by2.00 mmwith

purified

nonconducting water between them. A voltage of 6.00 V is applied

between

the

plates. Calculate

(i) the magnitude of theelectric fieldbetweenthe plates,

(ii)

the charge

stored

on

each

plate, and

(iii) the

charge

storedon

eachplate

if the

water

isremovedand

replaced with

air.

(8 marks)

d) Two

1.50-Vbatterieswith

their positive

terminals

in the samedirection are

inserted

in

series into the

barrel

of a flashlight. One battery has an

internal

resistance

of

0.255 Q the other aninternal resistance of 0.153

Q.

When the switch is closed, a

current of0.600 Apasses throughthelamp.

(i) Wh at is the

lamp s resistance?

(ii)

What

fractionof thepowerdissipated is dissipated in the batteries?

(9 marks)

QUESTION

4

a) Calculate the minimum wavelength x-ray that can be

produced

when a target is

struck by an electron that has been

accelerated

through a

potential

difference of

15.0kVand100kV.

(4 m arks)

b) What

current

is required in the windings of a long solenoid that has 1 000 turns

uniformly distributed over alengthof

0.400

m inordertoproducea magnetic

field

o f

magnitude

1.00

* 10~*T a t the center of the

solenoid?

(4 marks)

c)

Determine

(i) the

electric field

strength at a point 1.00 cm to the left of the

middle

charge

shown

in Figure 4.

(ii) the

magnitude

and

direction

of the

force

on it, if a

charge

of

-2.00 uC

is

placed

at

this

point, the

magnitude

and

direction

of the

force

on it?

6.00

ju

1.50/LtC

-2.00 >

3 .00cm-

*-2.00cm-

FIGURE

4

(8 m arks)

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d) Calculate

(iii)

the current in the wire if a potential difference of 9.0 V is applied

across

the

length

of thewire.

Given

the

wire

is a

34.5-m length

ofcopper

wire

at 20.0C

has a

radius

of 0.25 m m.

(iv)

The

current

in the wire if the

wire

is

heated

to

30.0C

while

the

9.0-V

potential

difference

ismaintained.

(9marks)

QUESTION 5

a) A conductorsuspended by twoflexible wires as shown inFigure 5 has a mass pe r

unit lengthof 0.040 0 kg/m. W hatcurrent mustexist in the conductor for the tension

in the supporting

wires

to bezero when themagnetic field is3.60T into the page?

Whatis the required direction for the current?

FIGURE

5

(4

marks)

b)

A

beam

of

light, traveling

in

air, strikes

the surface of

m ineral

oil at an

angle

o f

23.1

with

the normal to the surface. If the

light travels

at

2.17

=

10

8

m /s

through

the

oil,

whatis the

angle

o f

refraction?

(4 m arks)

c) CapacitorsCi

=6.0 uF and

C

2

= 2.0 uF are

charged

as a

parallel

combination

across

a

250-V battery.

The capacitors are disconnected from the battery and from

each

other.

They

are

then conne cted

positive

plate

to

negative plate

and negative

plate

to

positive

plate. Calculate the resultingchargeoneach capac itor.

(8 marks)

Hak Cipta

Universiti TeknologiMARA

CONFIDENTIAL


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d)

Calculate

(i) the

equivalent

resistance

between

points a and

b

in Figure 6.

(ii) the current in

each

resistor

if a potential difference of 34.0 V is applied

between points

a andb .

7.00ft

4.00

FIGURE

6

(9 marks)

QUESTION

6

a) The first

atomic

bomb released an energy equivalent to 20 kilotons of TNT. If 1 ton

of

TNT

releases

about 4.0 x 10

9

J, how

much

uranium was

fissioned

in

this bomb?

Assume

208 MeVreleasedpe rfission. Given atomic

mass

of

Uranium

is 235gmol

1

.

(4 m arks)

b)

A

step-up

transformer is

designed

to

have

an

output voltage

of 2 200 V

(rms)when

the

primary

is

connected across

a

11 0-V

(rms)source,

(i) Ifthereare 80turns on theprimarywinding, how manyturns arerequiredon

the secondary?

(ii) If a

load resistor

across the secondary draws a current of 1.5 A, what is the

current

in the primary,assumingideal

cond itions?

(4 marks)

c) A toaster ratedat 1 050 W operateson a120-V

household

circuit and has a4.00-m

length

of

nichrome wire

as its heating

element.

The

operating temperature

of

this

element is

32 0C.

What is the

cross-sectional

area o f thewire?

(8marks)

HakCipta Universiti Teknologi MARA

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CONFIDENTIAL

EH APR

2006 ENG012

d)

Below

questions is refered to

Figure

7:

(i) Find th eequivalent resistance of the circuit.

(ii)

If the total

power

supplied to the

circuit

is 4.00 W,

find

the emf of the

battery.

10.0ft

FIGURE

7

(9 marks)

END OF

QUESTIONPAPER

Hak CiptaUniversiti

Teknologi

MARA

CONFIDENTIAL


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