Light from a source passes through two polarizers whose axes are perpendicular (crossed). The intensity after the second polarizer is:
A$I_0/4$
B$I_0/2$
CZero
D$I_0$
Answer & Solution
Correct answer: C. Zero
Crossed polarizers ($\theta = 90°$): $\cos^2 90° = 0$ — no light passes. This is the basis of polarizer–analyser systems used to detect polarization.
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