Question

explain the following terms 
a.scattering  b.scattering angle  c. scattering center d. factors influencing scattering

Answer 1

SCATTERING: emission of light in various directions by an object is called scattering.
SCATTERING ANGLE: the angle between incident ray and direction in which the intensity of scattered light is observed is called scattering angle.
SCATTERING CENTRE: the objects through which light is scattered is called scattering centre.
FACTORS: wave length of light, humidity, refractive index

Answer 2

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.