Polarization is a phenomenon caused due to the wave nature of electromagnetic radiation. Let’s take light for example, light is an electromagnetic wave that travels through the vacuum of the space from the sun to the Earth. Electromagnetic waves are names so because they are created when an electric field interacts with a magnetic field. You will learn more about that later in the article, but now for some recap. In the chapter on waves, you learnt about two types of waves, Transverse waves and Longitudinal waves.
Transverse waves are waves i.e. movement of the particles in the wave is perpendicular to the direction of motion of the wave. For exam the ripples when you throw a stone in water. Longitudinal waves are when the particles of the medium travel in the direction of motion of the waves. For example, the motion of sound waves through the air.
An electromagnetic wave is created by the interaction of an electric field with a magnetic field. Light basically is the interaction of electric and magnetic fields travelling through space. The electric and magnetic vibrations of a light wave occur perpendicularly to each other. The electric field moves in one direction and magnetic in another though always perpendicularly. So we have one plane occupied by electric field, the magnetic field perpendicular to it and the direction of travel which is perpendicular to both. These electric and magnetic vibrations can occur in numerous planes. A light wave that is vibrating in more than one plane is referred to as unpolarised light. The light emitted by the sun, by a lamp or a tube light are all unpolarised light sources. As you can see in the image below, the direction of propagation is constant but the planes on which the amplitude occurs is changing.
The image here shows its various types:
The other kind of wave is a polarized wave. The polarization of light or any other wave refers to the removal of all but one plane so that the vibrations of the wave occur on only one plane. In the image above, you can see that a linearly polarized wave vibrates on only one plane. The process of transforming unpolarised light into the polarized light is known as polarization. The devices like the purple blocks you see are used for the polarization of light. There are few methods utilized in the polarization of light:
- Polarization by Transmission
- Polarization by Reflection
- Polarization by Scattering
- Polarization by Refraction
In the next article, we discussed the polarization of light using the methods listed above.
Practise This Question
|CBSE Physics Syllabus Class 6||CBSE Physics Syllabus Class 7||CBSE Physics Syllabus Class 8||CBSE Physics Syllabus Class 9||CBSE Physics Syllabus Class 10|