Define polarisation .

Polarisation is the restriction of the oscillations of a transverse wave to one plane , while the oscillations remain perpendicular to the direction of energy transfer.

Why can only transverse waves be polarised, and not longitudinal waves?

Polarisation restricts oscillation to a single plane perpendicular to the direction of travel. Longitudinal waves oscillate parallel to the direction of travel, so there is no perpendicular plane to restrict, meaning they cannot be polarised.

How does a polarising filter produce a polarised wave from an unpolarised wave?

A polariser consists of many parallel tiny slits. It only transmits waves oscillating parallel to the direction of the slits; waves in other planes are blocked.

Why do polaroid sunglasses with vertically oriented filters reduce glare?

Their transmission axis is vertical , so they block horizontally polarised light , only allowing vertically polarised light through.

If unpolarised light of intensity I 0 passes through a single polariser, the transmitted intensity falls to .......... of I 0 (the half rule).

If unpolarised light of intensity I 0 passes through a single polariser, the transmitted intensity falls to half of I 0 (the half rule).

True or False? Rotating an analyser by 90° relative to the polariser will still transmit some light.

False. At 90°, cos 2 (90°) = 0, so no light is transmitted — all the polarised light is absorbed by the analyser.

A LevelPhysicsCambridge (CIE)Flashcards7. WavesPolarisation

Polarisation (Cambridge (CIE) A Level Physics): Flashcards

Exam code: 9702

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Define polarisation.

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Cards in this collection (8)

Define polarisation.
Polarisation is the restriction of the oscillations of a transverse wave to one plane, while the oscillations remain perpendicular to the direction of energy transfer.
Why can only transverse waves be polarised, and not longitudinal waves?
Polarisation restricts oscillation to a single plane perpendicular to the direction of travel. Longitudinal waves oscillate parallel to the direction of travel, so there is no perpendicular plane to restrict, meaning they cannot be polarised.
How does a polarising filter produce a polarised wave from an unpolarised wave?
A polariser consists of many parallel tiny slits. It only transmits waves oscillating parallel to the direction of the slits; waves in other planes are blocked.
Why do polaroid sunglasses with vertically oriented filters reduce glare?
Their transmission axis is vertical, so they block horizontally polarised light, only allowing vertically polarised light through.
If unpolarised light of intensity I₀ passes through a single polariser, the transmitted intensity falls to .......... of I₀ (the half rule).
If unpolarised light of intensity I₀ passes through a single polariser, the transmitted intensity falls to half of I₀ (the half rule).
State Malus's law, and define the angle θ in the equation.
$I = I_{0} \cos^{2} (θ)$
θ is the angle between the transmission axes of the analyser and the polariser.
True or False?
Rotating an analyser by 90° relative to the polariser will still transmit some light.
False.
At 90°, cos²(90°) = 0, so no light is transmitted — all the polarised light is absorbed by the analyser.
Vertically polarised light of intensity I₀/2 is incident on an analyser whose transmission axis is at 60° to the vertical. Calculate the transmitted intensity in terms of I₀.
$I = \frac{I_{0}}{2} \cos^{2} (60 °) = \frac{I_{0}}{2} \times 0.25 = 0.125 I_{0}$

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