Q 12-10-027JEE MainEasy
Unpolarised light passes through three polaroids. The axis of the second is at $45°$ to the first, and the third is at $90°$ to the first. What percentage of the original intensity emerges?
Numerical value type. Enter your answer.
Answer: 12.5
Concept. First polaroid passes $\dfrac{I_0}{2}$; Malus's law at the next two.
Step 1. Intensity.
$$I = \frac{I_0}{2}\cos^245°\cos^245° = \frac{I_0}{8} = 12.5\%$$
Answer. $12.5$.
Solution by Sreeraj P, M.Sc Physics