QUESTIONS
SECTION A: (25 MARKS)
 Under which condition is the potential difference across the terminal of a cell equal to its e.m.f? (1mk)
 The figure below shows a ray of light incident on a plane mirror
Determine the angle of reflection when the mirror is rotated 10º anticlockwise (2mks)  A soldier standing some distance from a wall blows a whistle and hears its echo 1.8 seconds later. How far is the wall from the soldier? (Speed of sound in air = 330ms^{1}) (3mks)
 Other than temperature, state any other factor that affects the resistance of an ohmic conductor (1mk)
 Using the domain theory, differentiate between magnetic and nonmagnetic materials (1mk)
 The figure below shows circular waves approaching a plane barrier.
On the same diagram, sketch the reflected rays (1mk)  State one application of the following: (2mks)
 Convex mirrors
 Parabolic mirrors
 A pin is placed below the surface of transparent water of depth 10cm and refractive index 1.33. Calculate the vertical displacement of the pin (3mks)
 The figure below shows an arrangement of resistors in a circuit.
Determine: The effective resistance (2mks)
 The voltage drop across the 1Ω resistor (3mks)
 The figure below shows the image I formed by a concave mirror. Using ray diagrams, locate the position of the object (3mks)
 The figure below shows a displacementdistance graph of a wave travelling at 2ms^{1}
Determine: The amplitude (1mk)
 The wavelength (1mk)
 The frequency of the waves (2mks)
SECTION B (55MARKS)

 Draw the electric field pattern between the charges shown below (2mks)
 State two factors that affect the capacitance of a parallel plate capacitor (2mks)
 The figure below shows a network of resistor connected to a 100V power source.
Determine: The effective capacitance of the circuit (3mks)
 The charge on the 16uF capacitor (3mks)
 The p.d. across the 12uF capacitor (3mks)
 Draw the electric field pattern between the charges shown below (2mks)

 State the Snell’s law of refraction of light (1mk)
 The figure below shows a ray of light travelling from crown glass to air.
Determine: The refractive index of crown glass (3mks)
 The speed of light in crown glass. (3mks)
(Speed of light in air = 3.0 x 10^{8}ms^{1})

 What would be the effect on the image of increasing the length of a pinhole camera? (1mk)
 A girl stands 5m in front of a pinhole camera of length 50cm. If the girl is 1.2m tall, determine the size of her image as formed by the pinhole camera (3mks)
 The figure below shows an object in front of a plane mirror. Using rays, locate the image as seen by the eye shown (3mks)

 State the Ohms law (1mk)
 State the effect on the resistance of a conductor when the conductor is heated (1mk)
 Three identical dry cells each of e.m.f 1.6V are connected in series to a resistor of resistance 11.4Ω. If a current of 0.32A is flowing through the circuit, determine:
 the total e.m.f of the cells (1mk)
 the internal resistance of each cell (3mks)
 The figure below shows resistors R1 and R2 connected in parallel. Their ends are connected to a battery of potential difference V volts.
 In terms of V1, R1 and R2, write an expression for:
 Current I1 through R1 (1mk)
 Current I2 through R2 (1mk)
 Total current in the circuit (1mk)
 Show that the total resistance RT is given by (3mks)
RT = R1R2
R1+R2
 In terms of V1, R1 and R2, write an expression for:

 State two factors that affect the strength of an electromagnet (2mks)
 In the set up shown below, the suspended metre rule is balanced by the magnet and the weight shown. The iron core is fixed to the bench.
 State and explain the effect on the metre rule when the switch is closed (3mks)
 What is the effect of reversing the battery terminals? (1mk)
 State one defect of a simple cell and how it is corrected (2mks)

 Differentiate between transverse and longitudinal waves (2mks)
 State two conditions necessary for two progressive waves travelling in the opposite direction to form stationary waves (2mks)
 A wave has a periodic time of 0.2 seconds and a distance of 30cm between successive troughs. Determine the speed of the wave (3mks)
MARKING SCHEME
 When the cell is an open circuit
 r = 30 + (2 x 10)
= 50º  V = ^{2d}/_{t}
d = ^{Vt}/_{2}
=330 x 1.8
2
= 297  Temperature
length of conductor
crosssectional area of consuctor  In magnetic materials, the magnetic domains are aligned
In non magnetic materials the magnetic domains face in all directions 

 As a driving mirror or in supermarts
 reflectors
solar concatrators
 n = real depths
apparent depth
apparent depth = 10/1.33 = 7.52cm
displacement = 10  7.52 = 2.48cm 
 6 + 6
 I = V/R
= 2/4
= 0.5A
V = IR
= 0.5 x 1
=0.5


 2cm
 0.5  0 = 0.5m
 c = fλ
f = ^{c}/_{λ} = ^{2}/_{0.5} = 4HZ


 area of plates
distance apart of the plates
dielectric between the plates 
 Parallel C = 16 + 12 = 18μF
ct = 18 x 6 = 288 = 8.47μF
18 + 6 34  Q = CV
= 8.47 x 10^{6} x 100
= 8.47 x 10^{4}C
 Parallel C = 16 + 12 = 18μF


 The ratio of sine of the angle of incidence to the sine of the angle of refraction is a constant for a given pair of media

 C = 90  38 = 52º
n = ^{1}/_{sinC}
= ^{1}/_{sin52º}
= 1.27  n = ^{c}/_{c'}
c' = 3.0 x 10^{8}
1.27
=2.36 x 10^{8}ms^{1 }
 C = 90  38 = 52º

 It would be enlarged but less bright
 ^{H1}/_{H0} = ^{V}/_{u}
^{H1}/_{120} = ^{50}/_{500}
H1 = 50 x 120
500
=12cm
or
H1 = VH_{0}
u
=0.5 x 1.2
5
=0.12m


 The current flowing through a metallic conductor is directly proportional to the P.D across its ends provided the temperature and other physical conditions remain constant
 It increases

 1.6 x 3 = 4.8V
 E = I(r + R)
4.8 = 0.32(r + 11.4)
4.8 = 0.32r + 3.648
r = 4.8  3.648 = 3.6Ω
0.32
For each cell, r = ^{3.6}/_{3} = 1.2Ω


 I_{1} =^{ V}/_{R1}
 1_{2} = ^{V}/_{R2}
 IT = I_{1} + I_{2}
 I/RT = I/R1 + I/R2
1 = R1 + R2
RT R1 x R2
RT = R1 x R2 = R1R2
R1 + R2 R1 + R2


 amount of current
number of turns of the coil
soft ferromagnetic core 
 when the switch is closed the iron core become magnetised. The upper part of the iron core attains a south pole and attracts the metre rule which turns anticlockwise
 The polarity of the iron core is reversed and hence metre rule is repelled turning clockwise
 Local action  coat zinc with mercury
or
Polarization  add potassium dichromate solution
 amount of current

 In transverse waves, the vibrations are perpendicular to the direction of travel of the wave whereas in a longitudinal wave, the direction of vibration of the weave is the same direction of travel of the wave
 same speed
same frequency
same or nearly equal amplitude  V =fλ
= 5 x 0.3
1.5ms^{1}
f = ^{1}/_{0.2}
= 5HZ
λ = 30cm = 0.3M
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