State the condition necessary for the lunar eclipse to occur.

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You are provided with a charged electroscope, an insulator and a conductor. Describe how you would use these apparatus to distinguish the insulator from the conductor

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You are provided with two identical dry cells, two filament bulbs and a switch. Draw a circuit diagram that would make the bulbs have maximum brightness.

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Define the term magnetic field.

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The figure 1 below shows an object placed infront of a convex mirror. Using a ray diagram, locate the image position.

An FM radio broadcast at a frequency of 96.1 Hz. What is the wavelength of the broadcast?

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In the fig. 2, A B is a copper wire hanging from a pivot at A and dipping in mercury in a copper dish at B so that it hangs freely between the poles of a powerful magnet. The supports of the magnet are not included in the figure. Copper plate C is arranged such that AB=AC

Explain the observation that is made when switch S is closed.

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Figure 3 shows a plane wave incident on a concave reflector

On the same diagram draw the reflected wave showing its characteristics.

Fig. 4 shows an ammeter scale being used to measure current in a circuit

Determine the ammeter reading when connected through terminals C and A

An echo sounder sends sound signal to the bottom of a lake at an interval of 0.08 seconds. The first echo coincides with the third signal. If the speed of sound in water is 1400m/s, determine the depth of the Lake.

An electric bulb is rated 100W, 240V. Determine the resistance of the bulb.

State the conditions necessary for total internal reflection to occur.

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One of the possible causes of long sightedness is a short eye ball. State the other possible cause.

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In what form is energy lost in an electrical cable during transmission.

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a) Figure 5 shows two aluminium plates P and R placed parallel to each other. Plate P is charged with a high positive charge and connected to an uncharged gold leaf electroscope. Plate R is earthed.

State the effect on the divergence of golf leaf electroscope

i) When the distance of separation is increased. (1mk)

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ii) When R is moved in the direction shown. (1mk)

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iii) What effect does i and ii have on the capacitance of the plates? (2mks)

i) ............................................................................................................

ii) ............................................................................................................

b) Figure 6 shows an electrical circuit with three capacitors A, B and C.

Determine

i) The combined capacitance of the three capacitors (3mks)

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ii) The charge on the capacitor A. (3mks)

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iii) The potential difference across the capacitor B (2mks)

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a) What is the advantage in each case of transmitting power at:-

(i) Very high voltages? (1 mark)

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(ii). Alternating voltage? (1 mark)
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b) A large sub-station transformer is used to step down from 11000V to 450V. Determine the ratio of the turns in the primary to secondary coils. (3mks)

c) Fig.7 shows a 240V electric hair dryer with a plastic case.

i) State the colours of cables:

A.................................................................................................................. (1 mk)

B.................................................................................................................. (1 mk)

ii) One pin in the plug is not being used. State with a reason whether or not this makes the hair dryer dangerous. (2mks) ..................................................................................................................

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iii) Which switches need to be closed to switch on:

I. The fan alone? (1mk)

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II. The fan and one heating coil? (1mk)

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a) Figure 8 shows the main features of a cathode ray tube oscilloscope (CRO)

i) Describe how the electrons are produced in the tube. (2mks)

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ii) I. Name the part labelled Q. (1mk)

Q................................................................................................

II. State and explain the function of the part labelled Q. (3mks)

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iii) State what would be observed on the screen if an a.c. voltage is connected across the y- plates. (1mk) .................................................................................................................................... ....................................................................................................................................

b) The graph below shows relationship between kinetic energy and frequency of radiation

From the graph
i) State the relationship between K.E and frequency. (2mks)

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ii) Determine the threshold frequency and the work function of metal surface. (2mks)

a) The diagram below shows the paths taken by three radiations A,B and C, from a radioactive source through an electric field.

i) State the charge on plate Y. (1mk)

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ii) Identify the radiations A, B and C. A....................................................................................... (1mk)

B...................................................................................... (1mk)

C........................................................................................ (1mk)

iii) Give a reason why C deviates more than A. (1mk)

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b) In an x-ray tube, it is necessary to evacuate the tube. Explain. (1mk)

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c) A current of 5MA flows through an x-ray tube when anode voltage is 4.5x103V. Calculate

i) The number of electrons striking the target per seconds (2mks)

ii) The speed of electrons. Take the charge of an electron = 1.6x10-14C, mass of an electron = 9.1x10-31kg. (3mks)

a) The graph in the figure below shows the variation of magnification M with image distance V for a convex lens. Determine

b) A semi conductor diode and a resistor of constant resistance are connected in some way inside a box having two external terminals, as shown in figure.

When a potential difference V of 1.0V is applied across the terminals the ammeter reads 25mA. If the same potential difference is applied in the reverse direction the ammeter reads 50mA
i) I. Sketch a circuit diagram when the ammeter reads 25mA (1mk)

ii) Explain your diagram in (b) (i) above (2mks)

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iii) Sketch the circuit diagram when the ammeter reads 50MA (1mk)

iv) Explain your diagram in (iii) above (2mks)

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