CIE AS Level: Understanding Polarisation of Transverse Waves

Polarisation

Restriction of wave vibrations to one plane.

Transverse waves

Waves oscillating perpendicular to direction of travel.

Electromagnetic wave

Wave with electric and magnetic fields oscillating.

Unpolarised wave

Wave oscillating in multiple planes of oscillation.

Vertically polarised wave

Wave oscillating only in the vertical plane.

Horizontally polarised wave

Wave oscillating only in the horizontal plane.

Polarising filter

Device allowing oscillations in a specific plane.

Polarisers

Optical layers with parallel tiny slits.

Transmission axis

Direction through which a polariser transmits light.

Malus's law

Intensity of transmitted light depends on angle θ.

Intensity (I)

Power per unit area of light wave.

Half rule

Intensity of transmitted light is half unpolarised intensity.

Analyser

Second polarising filter after the first.

Cosine squared law

Intensity transmitted is I0cos²(θ).

Maximum intensity

Intensity when polariser and analyser align.

Minimum intensity

Zero intensity when polariser and analyser are perpendicular.

Angle θ

Angle between polariser and analyser's transmission axes.

Incident light

Light entering the polariser or analyser.

Transmitted light

Light that passes through the polariser or analyser.

Absorbed light

Light that does not pass through the analyser.

Intensity reduction

Intensity decreases when light passes through a polariser.

Polarisation by diffraction

Not applicable; diffraction does not polarise waves.

Longitudinal waves

Waves oscillating parallel to direction of travel.

Polarisation effects

Changes in light behavior due to polarisation.