What is Brewster’s angle in EM waves

Brewster’s angle, also known as the polarizing angle, is a specific angle of incidence at which light with a particular polarization is perfectly transmitted through a transparent dielectric surface, with no reflection. This phenomenon occurs when the reflected and refracted waves are perpendicular to each other.

Mathematically, Brewster’s angle $theta_B$ is given by:

Where:

• $theta_B$ is Brewster’s angle,

• $n_1$ is the refractive index of the medium from which the light is incident (typically air or vacuum),

• $n_2$ is the refractive index of the medium into which the light is transmitted (such as glass, water, etc.).

Key Points:

• Polarization of Light: At Brewster’s angle, the reflected light is fully polarized perpendicular to the plane of incidence. This means the reflected wave oscillates in one direction, with no component in the direction of the incident electric field.

• Reflection and Transmission: For light incident at Brewster’s angle, the reflectance for the p-polarized light (polarized parallel to the plane of incidence) goes to zero, meaning that all of the p-polarized light is transmitted into the second medium. However, for s-polarized light (polarized perpendicular to the plane of incidence), the reflectance is not zero.

• Applications: Brewster’s angle is useful in optical devices like polarizing filters, lasers, and in photography to reduce glare from surfaces like water or glass.

Example:

If light passes from air (with $n_1 = 1$) into glass (with $n_2 = 1.5$), Brewster’s angle is:

At this angle, the reflected light will be fully polarized.