Let the light rays fall on a surface at an angle. Normally,
light wave or rays are refracted or reflected in the directions known by the
laws.
Scattering of light is the
deviation of the light waves from directions of usual reflection and
refraction. Light waves or rays are scattered in all possible directions with
varying intensities.
The molecules of the medium in the path of light absorb light (energy) and
re-radiate it in all possible directions. All these molecules or atoms or
particles which re-radiate energy are called the Scattering Centers.
Scattering Angle: (see
diagram)
This is the angle between the incident wave (ray) and the scattered light wave.
Factors influencing scattering:
When the size of the objects (particles) on which the light waves are incident
is comparable to the wavelength, then scattering is very high and is inversely
proportional to 4th power of wavelength. So red light is scattered the least.
Scattering depends also on the refractive index of the medium (optical density)
or speed of light in the medium. If the medium is gas or air, then it depends
on the density or molecular concentration. If the medium is a solid and
the surface is very smooth then scattering is very less from that surface.
Scattering is more from a rough surface.
Scattering of light may also depend on whether light waves are polarized or
not.
Intensity of light or amount of light scattered in a direction depends on the
angle of scattering.
