State the laws of photoelectric emission.

Explanation

(i) For the given metallic surface, there is a certain frequency below which no photoelectric emission takes place.
(ii) The velocity or energy of photoelectrons depends upon the frequency of incident radiations and is independent of the intensity.
(iii) The process of photoelectric emission occurs instantaneously.
(iv) Photoelectric current is directly proportional to the intensity of incident light, but frequency of light should be greater than the threshold frequency.