NAME…………………………………………………
IDEX NO…………………….
SCHOOL…………………………………………………
CANDIDATES SIGN………
DATE……………………….
232/3
PHYSICS PAPER 3
MARCH/APRIL 2015
TIME : 2 HOURS
TIGANIAN WEST SUB-COUNTY-PRE MOCK EXAM 2015
Kenya certificate of secondary education (K.C.S.E)
PHYSICS
PRACTICAL
INSTRUCTION TO CANDIDATES
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Write your name and index number in the spaces provide above.
Answer all the questions in the space provided in the question paper.
You are supposed to spend the first 15 minutes of the 2½ hours allowed for this paper reading the
whole paper carefully before commencing your work.
Marks are given for a clear record of the observation actually made, their suitability, accuracy and
the use made of them.
Candidates are advised to record their observations as soon as they are made.
Mathematical tables and electronic calculators may be used
FOR EXAMINER USE ONLY
QUESTION
A
B
MAXIMUM SCORE
CANDIDATE SCORE
This paper consists of 8 printed pages.
Candidates must check to ascertain that all pages are printed as indicated
And that no question(s) is/are missing
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PART A
You are provide with the following apparatus,
1. A rectangular glass block,
2. A soft board,
3. White sheet of paper,
4. Optical pins,
5.
Thumb pins,
NB: you should have mathematical tables /calculator,geometrical set and a transparent ruler
Proceed as follows
(a)
Fix a white sheet of paper on the soft board using the thumb pins
(b)
Place the glass slab on the white piece of paper trace the outline of the glass slab on the paper
(c)
Stick two pins p1 and p2 so that the line joining them falls on the edge of the glass
obliquely, forming an angle of 150 with the normal NA.
(d)
(e)
Stick two other pins p3 and p4 so that they appear to be in line with the images of the
objects pins p1 and p2 in the slab as shown on the diagram below
Now remove the slab. Draw the lines joining p1 and p2 and also p3 and p4.Extend the two
lines to meet the outline of the block at the points A and B respectively. The lines p1 and
p2,AB and p3 and p4 show the path the ray follows as it passes from one medium to another:
air to glass and back to air again. Mark the directions with arrows.
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(f)
Measure the angle of refraction (r) between AB and the normal .record it in the table below
repeat the procedure for the angle of 300,450,600 and 750 and record the observation in the
table below
(5 marks)
Angle of
incidence (i0)
Angle of
refraction (r0)
150
300
450
600
750
Sin (i0)
Sin(r0)
(g)
Draw the graph of sin i0 (y-axis) against sin r0 (x-axis) in the grid provided below (5 marks)
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(h)
Determine the gradient of the graph and write down the equation of the graph
(i)
Compare the value of the refractive index ,n, if n=
paper you used
(2 marks)
sin i
using the pieces of white sheet of
sin r
(2 marks)
NB : Remember to hand in the pieces of white sheet of the paper you used
PART B
You are provided with the following
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2 dry cells
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A cell holder
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A nichrome wire
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An ammeter
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A voltmeter
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A jockey
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A switch
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8 connecting wires
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(a)
Set up the apparatus as show above
(b)
With the switch open, record the recordings E of the voltmeter
(c)
Place the jockey ,J, on the nichrome wire at 100cm mark. Close the switch , read and
record the values of I ( ammeter reading) and the corresponding values of V (voltmeter
reading) in the table below.
(d)
Repeat (c) above for the length ,L=70cm,60cm,50cm,40cm and 20cm.
Complete the table below
L (cm)
100
70
60
50
40
20
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I (A)
V (V)
E-V(V)
(e)
Plot a graph of (E-V) (y-axis) against I in the graph provided
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(f)
Determine the slope of the graph
(3 marks)
(g)
Given that E=V+Ir, from the graph determine
(i)
The internal resistance ,r, of the battery
(2 marks)
(ii)
V when I is 0.3A
(1 mark)
PART C
You are provided with the following apparatus
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Candle
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lens
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lens holder
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Meter rule
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Cross wire
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Screen
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Vernier call12ipers
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Proceed as follows.
(i)
Arrange the apparatus as shown below
(ii)
Place the cross wire infront of the lens so that U=28cm.The lit candle should be placed
close to the cross wire.
(iii)
Adjust the position of the screen until a sharp image is cast on the screen.
(iv)
Measure and record the value of image distance ,V, in the table.
(v)
Repeat the same procedure for the other values in the table
U(cm)
V(cm)
M=V/U
30
36
(2 marks)
(vi)
Given that the focal length f of the lens satisfies the equation f=
average value of the focal length
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V
determine the
M
(3 marks)
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End