(a(i))[2]
Explain what is meant by the term photon.
(a(ii))[1]
State one piece of evidence, using the intensity of light, that the photoelectric effect provides for the particulate nature of light.
(b)[5]
Some electron energy levels in a solid are shown in Fig. 11.1. A semiconductor material has a very high resistance in darkness. When light falls on the semiconductor material, its resistance decreases. Explain the resistance of the semiconductor material in different light conditions.