JEE Mains · Physics · STD 12 - Wave optics
- JEE Mains 2021
- Medium
- Numerical
A source of light is placed in front of a screen. Intensity of light on the screen is \(I.\) Two Polaroids \({P}_{1}\) and \({P}_{2}\) are so placed in between the source of light and screen that the intensity of light on screen is \({I} / 2 .\) \({P}_{2}\) should be rotated by an angle of ........ (degrees) so that the intensity of light on the screen becomes \(\frac{3 I}{8}.\)
Pick an option to check your answer.
Answer & Solution
Correct Answer
(B) \(30\)
Step-by-step Solution
Detailed explanation
\(I=\frac{I_{0}}{2} \cos ^{2} \phi\)
\(\frac{I}{2} \cos ^{2} \phi=\frac{3 I}{8}\)
\(\cos ^{2} \phi=\frac{3}{4}\)
\(\cos ^{2} \phi=\frac{\sqrt{3}}{2}\)
\(\Rightarrow \phi=30\)
More questions from Physics
- Match List-I with List-II.
List-I List-II A. Meter (L) I. \(\sqrt{\dfrac{hc}{G}}\) B. Second (S) II. \(\sqrt{\dfrac{Gh}{c^5}}\) C. Kilogram (M) III. \(\sqrt{\dfrac{K^2L^2c^3}{Gh}}\) D. Kelvin (K) IV. \(\sqrt{\dfrac{Gh}{c^3}}\)
where \(h\) (Planck's constant), \(G\) (gravitational constant) and \(c\) (speed of light in vacuum) as fundamental units.
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