Laws of photo electric effect

Here are the laws of the photoelectric effect:

1. Intensity of Light: The photoelectric current (the rate at which electrons are emitted) is directly proportional to the intensity of the incident light, provided the frequency of the light is above the threshold frequency.

2. Frequency of Light: For each photosensitive material, there is a minimum or threshold frequency (ν₀) below which no photoelectric emission occurs, regardless of the intensity of the incident light. Above the threshold frequency, the kinetic energy of the emitted electrons increases linearly with the frequency of the incident light.

3. Instantaneous Emission: The emission of photoelectrons is practically instantaneous upon illumination of the surface, provided the frequency of the incident light is above the threshold frequency. There is no time lag.

4. Kinetic Energy of Emitted Electrons: The maximum kinetic energy of the emitted photoelectrons depends on the frequency of the incident light and the work function of the material, but it is independent of the intensity of the incident light. The relationship is given by Einstein's photoelectric equation: KE_max = hν - φ, where h is Planck's constant, ν is the frequency of incident light, and φ is the work function of the material.