Polarization Of Light - Practice Questions & MCQ

Polarization of light-

While writing the equation for light wave,

                                                                 $E=E_0 \sin \omega(t-x / v)$

we assumed that the direction of electric field is fixed and the magnitude varies sinusoidally with space and time. So the electric field in a light wave propagating in free space is perpendicular to the direction of propagation. But there may be infinite number of directions perpendicular to the direction of propagation and the eletric field may be along any of these directions. But If the electric field at a point always remains parallel to a fixed direction and remain parallel as the time passes, the light is called linearly polarized along that direction. The same is also called plane polarized light. The plane containing the electric field and the direction of propagation is called the plane of polarization. This can be better understand by the following figure.

Unpolarised light-

In ordinary light (light from bulb, sun, etc.), the electric field vectors are distributed in all directions in a light is called unpolarized light. This resolved into horizontal and vertical component i.e., the electric field.

Polarised light -

The phenomenon of limiting the vibration of electric field vector in one direction in a plane perpendicular to the direction of propagation of light wave is called polarization of light.

The plane in which oscillation occurs in the polarised light is called plane of oscillation. The plane perpendicular to the plane of oscillation is called plane of polarization. Light can be polarized by transmitting through certain crystals such as tourmaline or polaroids.

Polaroid
It is a device used to produce the plane polarized light. It is based on the principle of selective absorption. Polaroids allow the light oscillations parallel to the transmission axis pass through them. The crystal or polaroid on which unpolarized light is incident is
called polarizer. Crystal or polaroid on which polarized light is incident is called analyzer.