Unpolarized light passes through a combination of two ideal polarizers.The transmission axes of the first polarizer and the second polarizer are at 30.0° to each other.What percentage of the original light gets through the combination?
A)37.5%
B)50%
C)75%
D)100%

Question

Quizplus · Accepted Answer

The intensity of light after passing through two polarizers with their axes at an angle θ to each other is given by Malus's law, I = I₀cos²θ, where I₀ is the initial intensity and θ is the angle between the polarizers. Here, θ = 30°, so the percentage of original light that gets through is I/I₀ = cos²(30°) = (sqrt(3)/2)² = 3/4 = 75%. However, since the light is initially unpolarized, only half of this light gets through the first polarizer, so the final percentage is 75%/2 = 37.5%.

Unpolarized Light Passes Through a Combination of Two Ideal Polarizers