Structure of Atom
10.0 Photoelectric Effect
10.0 Photoelectric Effect
- The phenomenon of emission of electrons from the surface of a photo-irradiated metal is called photoelectric effect.
- For a given metal, emission will take place only when the frequency of the irradiated light is above a certain value characteristic of that metal.
- The number of electrons ejected is proportional to the intensity or brightness of light.
- Einstein (1905) was able to explain the photoelectric effect using Planck’s quantum theory of electromagnetic radiation.
- Kinetic energy of the ejected electron is proportional to the frequency of the electromagnetic radiation.
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Threshold Frequency(${\nu _o}$)
Minimum frequency of photon required to eject the photoelectron from metal surface.
Threshold Wavelength(${\lambda _o}$)
Maximum wavelength of light required to eject the photoelectron from metal surface.
Work Function(W)
Minimum Energy of photon required to eject the photoelectron from metal surface.
$$h\nu = h{\nu _o} + \frac{1}{2}m{v^2}$$
If frequency of light is greater than ${\nu _o}$, then part of energy is used for work function and remaining part provides kinetic energy to photoelectron.
