Question

An unpolarised beam of intensity $I_0$ is incident on a pair of nicols making an angle of ${60}^0$ with each other. The intensity of light emerging from the pair is :

• A. $I_0$
• B. $I_0/2$
• C. $I_0/4$
• D. $I_0/8$

Answer 1

The correct option is D $I_0/8$

After passing from first nicol the intensity will be reduce by 50%

$I^{\prime }=\frac{I_0}{2}$

Then it will pass from second nicol

According to Malus' law

$I=I_{0}co{s}^2\theta =I_0\left(co{s}^2{60}^0\right)$

$I^{\prime }\times {\left(\frac{1}{2}\right)}^2=\frac{I^{\prime }}{4}=\frac{I_0}{8}$