Question

State the laws of photoelectric emission.

Or

What is photoelectric effect? State and explain the laws relating to this effect.

Answer 1

Law of photoelectric emission are four definitions of photoelctric effect:

1. The velocity of electrons emitted is independent of the intensity of light and depend only upon the frequency (or wavelength) of the incident light.
2. Photoelectric current (or the number of photoelectrons ejected per second) is proportional to intensity of incident light. 
3. For a given metal, there exists a certain minimum frequency below which the emission of electrons stops completely. This frequency is called the threshold frequency.
4. Photoelectric emission is an instantaneous process.