K.C.S.E Physics Q & A - MODEL 1998PP2QN04

K.C.S.E Physics Q & A - MODEL 1998PP2QN04

a) In an experiment to determine the rate at which solar energy is absorbed by a surface, an aluminum block, coated black and fitted with a heater (Fig. 3) is exposed to the sun, for a period of time. The temperature rise in noted. After the temperature of the block is allowed to fall to the initial temperature, the block is electrically heated to the temperature.

(i) Draw and labeled a circuit diagram that would be used to determine the electrical energy.
(ii) State the measurements that would be taken in (a)(i) to determine the rate of heating of the block.
(iii) Explain how the measurements stated in (a) (ii) would be used to determine the rate of heating of the block by the sun.
b) Fig 4 shows a photocell

(i) Label the cathode and anode.
(ii) How are electrons produced in the cell
(iii) Draw a simple circuit including the photocell to show the direction of flow of current
(iv) Calculate the photon energy in ultraviolet radiation whose frequency is 8.60 x 10¹⁴ HZ. (Plank's constant h=6.63 x 10^-34 Js)

ANSWERS