Polarization is a property of some types of light wave that describe the orientation of their oscillations. If the wave oriented only to a single direction is called polarization or simply polarized light.
The light wave is an electromagnetic wave that travels through the vaccum of outer space. Light wave are produced by vibrating electric charges. The nature of such electromagnetic waves is a transverse wave that has both an electric component as well as a magnetic component. The light wave which is vibrating in more than one direction is referred to as unpolarised light.
We can produce polarized light from unpolarised (ordinary) light by under way-
1. Produced by reflection
2. Produced by refraction
3. Produced by double refraction
1. Produced by Reflection: When unpolarised light is incident at an angle ,the light that is reflected from the surface has become perfectly polarized light. We can prove that the tangent of the incident angle (polarizing angle) is numerically equal to the refractive indices of the medium that is µ=tan ip
where ip= angle of polarization and µ= refractive indices of the medium
2. Produced by Refraction: When unpolarised light is passes from one medium (air) to other medium (crystal), the path of the emerging beam changes its direction. The light wave occurs in a plane perpendicular to the surface has becomes plane polarized light.
3. Produced by double refraction: Few transparent crystal, such as calcite and quartz have the property after passing the unpolarised (ordinary) light through them, the refracted light is split into two parts. One of the beam follow Snell’s law of refraction is called ordinary beam (ray).The other beam is not follow Snell’s law is called extra ordinary beam (ray). Both of them are plane polarized light and the directions of their vibrations are at right angles to each other.
Application of polarization:
- It is used for infrared spectroscopy.
- Polaroid filter can be used to perform stress analysis test on transparent plastic in engineering industries.
- Polarization is also used in the 3-D movies.
- It can be used on satellite communication to separate transmission on given frequency.
- It can also used for providing information on sources of radiation and scattering etc.
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