State the four laws of photoelectric emission.

Explanation

Laws of photoelectric emission :
1. Photoelectric emission takes place from a metal surface, when frequency of incident light is above its threshold frequency.
2. The photoelectric emission starts as soon as the light is incident on the metal surface.
3. The maximum kinetic energy with which an electron is emitted from a metal surface is independent of the intensity of the light and depends upon its frequency.
4. The number of photoelectrons emitted is independent of the frequency of the incident light and depends only upon its intensity.