Question

An unpolarised beam of intensity \( I_0 \) is incident on a pair of nicols making an angle of \( 60^\circ \) with each other. The intensity of light emerging from the pair is

• A. \( I_0 \)
• B. \( \frac{I_0}{4} \)
• C. \( \frac{I_0}{2} \)
• D. \( \frac{I_0}{8} \)

Hint:

Use \( I = I_0 \cos^2\theta \) after the first polaroid reduces unpolarized light to \( \frac{I_0}{2} \).

Answer 1

The Correct Option is D

For unpolarized light passing through two polaroids (Nicols): - First polaroid reduces intensity by half: \( I_1 = \frac{I_0}{2} \) - Second polaroid: \[ I = I_1 \cos^2\theta = \frac{I_0}{2} \cos^2(60^\circ) = \frac{I_0}{2} \times \left( \frac{1}{2} \right)^2 = \frac{I_0}{8} \]