Scattering of light
Tyndall was the first to study experimentally the scattering of light. When a parallel beam of light passes through a gas or liquid, a part of it appears in directions other than that of the incident light. This phenomenon is called scattering of light. The scattering is due to absorption of light by the molecules of the medium and its re-radiation in different directions. Scattering of light is of two types
- Coherent scattering:If the scattered light has the same wavelength as the incident light it is called coherent scattering. Example: Rayleigh’s scattering.
- Incoherent scattering:If the scattered light has a wavelength different from that of the incident light, it is called incoherent scattering. Example: Raman scattering.
Rayleigh’s scattering Rayleigh studied the scattering of light by air molecules. He found that the amount of scattering depends on the wavelength of the light and also the size of the particle which causes scattering.
Rayleigh’s scattering law states that the amount of scattering of light is inversely proportional to the fourth power of its wavelength.