The following items are positioned in sequence: A source of a beam of natural light of intensity I₀,three ideal polarizers A,B,and C;and an observer.Polarizer axis angles are measured clockwise from the vertical,as viewed by the observer.The axis angle of polarizer A is set at 0° (vertical),and the axis angle of polarizer C is set at 50°.The axis angle of polarizer B is set at 120°.What is ratio of the intensity of the beam at the observer to the intensity I₀ of the source? A)0.015 B)0.020 C)0.025 D)0.030 E)0.035

Question

Quizplus · Accepted Answer

The intensity after passing through the first polarizer A is I₀/2. After passing through polarizer B, the intensity is (I₀/2) * cos²(120° - 0°) = (I₀/2) * (1/4) = I₀/8. After passing through polarizer C, the intensity is (I₀/8) * cos²(50° - 120°) = (I₀/8) * cos²(-70°) = (I₀/8) * (0.342)² ≈ 0.015I₀.

The Following Items Are Positioned in Sequence: a Source of a Beam