Polarisation of Light

The phenomenon of restriction of the vibration of light waves in a particular plane perpendicular to the direction of wave motion is called polarisation of light.

or

The phenomenon of confining the vibrations of the electric vector to a particular direction perpendicular to the direction of propagation of light is called Polarization.

When the displacement of the particle is perpendicular to the direction of propagation of the wave, then it is said to be transverse wave.

The wave in which the vibration of electric field vectors are confined in one plane and parallel to one unique direction is called linearly polarised wave; it is also referred to as plane polarised wave.

When the plane of vibration of a wave is changed randomly in very short intervals of time, such waves are called unpolarised waves.

A thin film of ultramicroscopic crystals used to produce plane polarised light is called a polaroid.

Statement: When plane polarised light is incident on an analyser, the resultant intensity of light transmitted from the analyser varies directly as the square of the cosine of the angle between the plane of transmission axis of the analyser and polariser.

Formula:

Where:

• I₀ = intensity of plane polarised light
• I = intensity of transmitted light from the analyser
• θ = angle between the axis of the polariser and the analyser

The plane in which vibrations are present is called the plane of polarisation.

The plane in which E vibrates/oscillates is known as the plane of vibration.