Question

The relation \( I = I_0 \cos^2 \theta \) is (I\( _0 \) - Intensity of incident light on the analyser, I - intensity of emergent light from the analyser, \( \theta \) - angle between plane of polarization and the axis of analyser)

• A. Newton's law
• B. Snell's law
• C. Brewster's law
• D. Malus's law

Hint:

Remember the fundamental laws of optics related to polarization. Malus's law specifically deals with the intensity of polarized light after passing through an analyser as a function of the angle between the polarization plane and the analyser's axis.

Answer 1

The Correct Option is D

The given relation \( I = I_0 \cos^2 \theta \) describes the intensity of polarized light after it passes through a polarizing analyser.
Here: - \( I_0 \) is the intensity of the polarized light incident on the analyser.
- \( I \) is the intensity of the light transmitted through the analyser.
- \( \theta \) is the angle between the plane of polarization of the incident light and the transmission axis of the analyser.
This relationship is known as Malus's law, which states that the intensity of plane-polarized light after passing through a polarizer is proportional to the square of the cosine of the angle between the plane of the incident light and the transmission axis of the polarizer.
Let's briefly recall the other laws mentioned: - **Newton's laws** are laws of motion describing the relationship between a body and the forces acting upon it, and its motion in response to those forces.
- **Snell's law** describes the relationship between the angles of incidence and refraction when light passes through the interface between two different isotropic media, such as air and glass.
- **Brewster's law** describes the relationship between the angle of incidence at which light with a particular polarization is perfectly transmitted through a transparent dielectric surface, with no reflection.
This angle is known as Brewster's angle or the polarization angle.
Therefore, the relation \( I = I_0 \cos^2 \theta \) is Malus's law.