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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
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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)
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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)
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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)
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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
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