Written by the Fiveable Content Team • Last updated August 2025
Written by the Fiveable Content Team • Last updated August 2025
Definition
The axis of a polarizing filter is the direction along which the filter allows light waves with specific orientations to pass through. It determines the plane of polarization for transmitted light.
The axis of a polarizing filter is usually marked on the frame or edge of the filter.
A polarizing filter only allows light waves vibrating parallel to its axis to pass through.
When two polarizing filters are placed perpendicular to each other, they block all light from passing through.
The intensity of transmitted light through a polarizing filter can be described using Malus's Law: $I = I_0 \cos^2(\theta)$, where $\theta$ is the angle between the light’s initial polarization direction and the filter's axis.
Polarizing filters are commonly used in sunglasses and cameras to reduce glare.