Name: Waves and Their Phases
Uploaded: 2019-07-19
Duration: 6 min 51 s
Description: In this video, we will learn how two or more waves can be studied in terms of their phases. Equations of two waves and graphs of two waves. Learn more!

Question

What is polarisation? Interpret polarisation with the help of electric vector. Make it clear why it is a property of transverse wave only?

Accepted Answer

The phenomenon of diffraction and interference is the example that proves the wave nature of light. But the type of wave is not revealed in that. Whether the light is a transverse wave or the longitudinal wave, this nature is only shown by the process of polarisation. This is known that the phenomenon of polarisation can only take place in transverse wave and the light wave undergoes polarisation, which shows that the light wave is a transverse wave. Earlier it was considered that the light is a longitudinal wave but the scientist, Huygen proved by his experiments that light is a transverse wave by showing polarisation in light.

In ordinary light, the electric field vector $\vec{E}$ vibrates with many components in a plane perpendicular to the direction of propagation such that $\vec{E}, \vec{B}$ and direction of propagation are perpendicular to each other. Polarisation is a method by which we restrict $\vec{E}$ in a particular plane consisting of the direction of propagation and direction of oscillation. Only transverse waves can be polarised because it is in $3 D$ shape which means $\vec{E}$ & $\vec{B}$ vectors are oscillating in every direction perpendicular to that of the propagation. Hence it can be restricted in one $2 D$ plane. But vibration in a longitudinal wave is propagation along $1 D$ , so it is impossible to make them in a plane.

What is polarisation? Interpret polarisation with the help of electric vector. Make it clear why it is a property of transverse wave only?

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