Brewster’s angle

Definition

Brewster's angle is the angle of incidence at which light with a particular polarization is perfectly transmitted through a transparent dielectric surface without any reflection. It occurs when the refracted and reflected light rays are perpendicular to each other.

5 Must Know Facts For Your Next Test

1. At Brewster's angle, the reflected light is completely polarized parallel to the incident surface.
2. The formula for Brewster's angle is $\theta_B = \tan^{-1} \left( \frac{n_2}{n_1} \right)$, where $n_1$ and $n_2$ are the refractive indices of the two media.
3. Brewster's angle depends on the wavelength of the light because different wavelengths have different refractive indices.
4. When unpolarized light hits a surface at Brewster's angle, only light polarized perpendicular to the plane of incidence will be refracted.
5. Brewster's angle is also known as the polarization angle.

Review Questions

• What happens to reflected light at Brewster's angle?
• How do you calculate Brewster's angle?
• Why does Brewster's angle depend on the wavelength of light?

Related terms

Polarization: The orientation of oscillations in the plane perpendicular to a wave’s direction of travel.

Refractive Index: A measure of how much a ray of light bends when it enters that material.

Snell's Law: $n_1 \sin(\theta_1) = n_2 \sin(\theta_2)$; it describes how waves change direction when they pass from one medium into another.