Question

A beam of natural light falls on a system of $6$ polaroids, which are arranged in succession such that each polaroid is turned through ${30}^o$ with respect to the preceeding one. The percentage of incident intensity that passes through the system will be

• A. $100$%
• B. $50$%
• C. $30$%
• D. $12$%

Answer 1

Answer: (D)

$12$%

If $I$ is the final intensity and $I_0$ is the initial intensity then,

$I=\frac{I_0}{2}({\cos }^{2}30{)}^5$

$\frac{I_0}{I}=\frac{1}{2}\times {\left(\frac{\sqrt{3}}{2}\right)}^{10}=0.12=12percent$