CBSE NOTES CLASS 12 PHYSICS
CHAPTER 11 DUAL NATURE OF RADIATION AND MATTER
Laws of photoelectric effect
- Effect of frequency on photoelectric current
The stopping potentials are in the order V03 > V02 > V01 if the frequencies are in the order ν3 > ν2 > ν1. That is greater the frequency of incident light, greater is the maximum kinetic energy of the photoelectrons. Consequently, we need greater retarding potential to stop them completely.
For a given photosensitive material, there is a certain minimum cut-off frequency, called threshold frequency, below which there is no emission of photoelectrons takes place, no matter how intense the incident light is.
Above the threshold frequency, the stopping potential or equivalently the maximum kinetic energy KE of the emitted photoelectrons increases linearly with the frequency of the incident radiation, but is independent of its intensity.