Plane-polarized light of intensity I₀ is incident on an ideal analyser whose transmission axis rotates uniformly with angular speed Ω. What is the time period of the transmitted-intensity variation?
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Question

Plane-polarized light of intensity I₀ is incident on an ideal analyser whose transmission axis rotates uniformly with angular speed Ω. What is the time period of the transmitted-intensity variation?

Options

G1 Physics · Accepted Answer

If the analyser angle is θ = Ωt, Malus' law gives I(t) = I₀ cos²(Ωt). The function cos²x repeats when x increases by π. Therefore the time period T satisfies ΩT = π. Hence, T = π ÷ Ω. Correct option: B.