Polarizers in Action Quiz

A polarizer selects one component of vibration. The first polarizer selects one vibration direction. The transmitted light is then mostly vibrating along the polarizer’s transmission axis.

Alignment maximizes transmission for polarized light. Alignment lets the polarized light through. When both axes match, the second polarizer does not block the direction created by the first.

The second polarizer passes what the first produces if aligned. The second polarizer passes the same polarization as the first. This gives the greatest transmission possible for that pair (though still reduced compared with the original unpolarized light).

Perpendicular axes block the transmitted polarization. Crossed polarizers block. Light after the first polarizer has one vibration direction, and the second polarizer rejects that direction when axes are 90° apart.

Glare from flat surfaces is often horizontally polarized. Sunglasses are designed so their transmission axis is vertical, which blocks much of the horizontal glare.

Rotation changes the axis relative to the glare polarization. When alignment blocks the glare’s main vibration direction more strongly, the glare appears dimmer.

Transmission depends on the relative angle of the axes. Rotating changes transmission and brightness. If the filters are polarizers, the overlap region goes from bright (aligned) to dark (crossed).

Polarizers require transverse oscillations. Polarization is for transverse waves. Sound in air oscillates along its direction of travel, so there is no sideways vibration direction to block.

A polarizer transmits one e-field component. The filter transmits one component and blocks the perpendicular one. The blocked component is typically absorbed (or strongly attenuated) by the polarizing material.

LCDs need polarizers to convert polarization changes to brightness. LCDs use polarizers to control light passing through.

Half-intensity transmission for unpolarized light. About half passes on average. This comes from averaging many random polarization directions relative to the polarizer axis.

Polarizers change polarization and intensity, not frequency. Frequency remains the same; intensity and polarization change.

Only the component parallel to the axis is transmitted. The perpendicular component is absorbed/blocked.

Polarizers reduce polarized reflections and glare. They work best when reflections are strongly polarized, such as at certain viewing angles.

Reflection can favour certain vibration directions. This is why glare often has a dominant polarization that can be filtered.

Intermediate axes allow partial transmission in stages. The middle polarizer produces a new polarization direction that is not fully blocked by the last.

A middle polarizer at an intermediate angle reduces the mismatch. A middle polarizer at 45° lets some light through both others.

Real polarizers have absorption and imperfect transmission. Even when aligned, transmission is less than 100% due to material losses.

Polarization can come from filtering, reflection, or scattering. A, B, and D can create partially polarized light.

Polarizers select vibration direction to reduce unwanted light. They filter vibration direction and reduce unwanted reflections.