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. $I_0/2$
• C. $I_0/4$
• D. $I_0/8$

Answer 1

Answer: (C)

$I_0/4$

Answer 2

According to Malus' law
$I =I_{0}\, \cos ^{2} \theta= I _{0}\left(\cos ^{2} 60^{\circ}\right)$
$=I_{0} \times\left(\frac{1}{2}\right)^{2}=\frac{I_{0}}{4}$