Name:……………………………………………………………………….. Index No.: ………
School:……………………………………………………………………… Sign.: …………
Date:……………………
Kenya Certificate of Secondary Education (
K.C.S.E )
232/2
PHYSICS
PAPER 2
(THEORY)
JULY/AUGUST
TIME: 2 HOURS
SCHOOL BASED ASSESSMENT EXAM A
PAPER 2
FORM
4
PHYSICS
PAPER
2
INSTRUCTIONS TO
CANDIDATES:
·
Write your name, admission number and the name of your
school in spaces
·
Sign and write the date of examination in the spaces
provided above.
·
This paper consists of sections: A and B.
·
Answer all the questions in section A and B in the spaces provided below
each question.
·
All
working must
be clearly shown where necessary.
·
Mathematics tables and silent
electronic calculators may be used.
FOR
EXAMINER’S USE ONLY
SECTION
|
QUESTION
|
MAXIMUM SCORE
|
CANDIDATE’S SCORE
|
A
|
1 – 13
|
25
|
|
B
|
14
|
09
|
|
15
|
10
|
||
16
|
09
|
||
17
|
10
|
||
18
|
09
|
||
19
|
08
|
||
TOTAL SCORE
|
80
|
||
This
paper consists of 8 printed pages.
Candidates
should check to ascertain that all pages are printed as indicated
and
that no questions are missing.
SECTION
A (25 MARKS)
Answer ALL questions in this section in the spaced provided.
1. Convex mirrors are used in cars as driving
mirrors because they have a wide field of view.
Sketch a labelled diagram to show the wide field of view. (2marks)
2. Cathode ray oscilloscope (CRO) is more
accurate voltmeter that moving coil voltmeter.
Give two reasons in support to this statement. (2marks)
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3. Differentiate between electromotive force and
potential difference. (2marks)
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4. Arrange the following electromagnetic waves
in the order of increasing wavelength.
Ultraviolet, x – rays, radiowaves, g – rays. (1mark)
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5. Distinguish between thermionic and
photo-electric emission. (1mark)
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6. Bulb x lights while bulb
y does not. Explain. (2marks)
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7. The figure below shows a
ray of light traveling through water, whose refractive index is 1.33 and glass.
Determine the refractive index of glass. (3marks)
8. The figure shows an
object O in front of a curved mirror M, on the same figure, locate the image. (3marks)
9. Determine the total capacitance of the
arrangement below. (1mark)
10. Indicate the poles of the
electromagnet shown in the figure below. (1mark)
11. What is meant by threshold frequency as used in
photoelectricity. (1mark)
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12. Give the difference between real and virtual
image. (2marks)
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13. The following is part of a radioactive decay
series.
Determine the values of a and b. (2marks)
14. Figure 3 below shows a transverse wave
traveling along x-axis.
Determine from the graph in figure 3 above:-
i) The wavelength of the
wave. (1mark)
ii) The amplitude of the
wave. (1mark)
SECTION B: (55 MARKS)
Answer all questions in this section in the space provided.
15. a) State
Ohm’s Law. (1mark)
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b) A wire was connected to
a battery and it was found that the energy converted to heat was 30J when 20C of charge
flowed through the wire in 5 seconds.
Calculate:-
i) The p.d between the ends of the wire. (2marks)
ii) The current flowing through the wire. (2marks)
iii) The resistance of the wire. (2marks)
iv) The average power development in the wire. (2marks)
c) The graph shows results obtained in an
experiment to determine the e.m.f (E) and the internal resistance , r, of a
cell.
Given that the equation of the graph is .
Use the graph to determine the values of:-
i) E (2marks)
ii) r (3marks)
16. a) State
one cause of energy losses in a transformer and explain how it can be
minimized.(2marks)
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b) A transformer is
designed to supply a current of 7.5A at potential difference of 100V to a motor
from an a.c supply of 240V. If the efficiency of the transformer is 85%.
Calculate:-
i) The power supplied to the transformer. (2marks)
ii) The current in the primary coil (2marks)
c) The figure shows a cross-section of a
bicycle dynamo. The wheel is connected
by an axle to a permanent cylindrical magnet and is rotated by the bicycle
tyre.
i) Explain why the bulb
lights. (1mark)
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ii) How can the bulb be
made brighter? (1mark)
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17. a) The
figure below shows a bridge rectifier.
i) Define the term rectification. (1mark)
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ii) Describe how the illustrated rectifier works (2marks)
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iii) What modifications can we make on the
arrangement to improve the quality of the output (1mark)
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iv) Sketch
on the areas below how the improved output is displayed on a C.R.O screen. (1mark)
b) The figure below shows an expansion cloud
chamber.
i) What is the purpose of the
Vapour? (1mark)
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ii) Explain how the
radiations emitted by the radioactive source in the chamber are detected. (2marks)
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18. a) The
diagram below shows part of x-rays tube.
Name parts:- (2marks)
P
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Q .......................................................................
b) i) What is the effect on the wavelength of
x-rays if the number of electrons hitting metal target are increased. (1mark)
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ii) What is the effect on wavelength of x-rays
when p.d across the tube is decreased (1mark)
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c) Calculate the maximum velocity of electrons
that would produce x –rays of frequency 8.0 x 108Hz if only 20% of kinetic
energy is converted to x-rays. (Take
planks constant = 6.63 x 10-35Js). (2marks)
d) An x-ray tube operating at a potential
difference of 50kV has a tube current of 20mA.
Calculate:-
i) The electric power
input. (2marks)
ii) The number of electrons
hitting the target per second. (2marks)
iii) The velocity of the
electrons when they hit the target. (3marks)
19. I. The
figure below shows how a near object O is focuses in a defective eye,
a) What problem does the
observer face when viewing an object at the near point. (1mark)
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b) i) Sketch on the same figure how a distant
object is focused by the eye. (2marks)
ii) State the nature of the defect. (1mark)
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c) i) A
pastor is known to have the defect stated in (b) (ii) above how will the pastor handle a bible as
he read it. (1mark)
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ii) How would you advise
the pastor as he goes about correcting the defect. (1mark)
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II. a)
Show on the
diagram the path of the incident ray after striking AB of glass prism whose
refractive index is 1.5 through the prism. (4marks)
b) Give two advantages of using optical
fibres instead of copper wires in transmission of messages. (2marks)
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