Optics Question 114
Question: A small plane mirror placed at the centre of a spherical screen of radius R. A beam of light is falling on the mirror. If the mirror makes n revolution. per second, the speed of light on the screen after reflection from the mirror will be
Options:
A) 4pnR
B) 2pnR
C) $ \frac{nR}{2\pi } $
D) $ \frac{nR}{4\pi } $
Show Answer
Answer:
Correct Answer: A
Solution:
When plane mirror rotates through an angle q, the reflected ray rotates through an angle 2q. So spot on the screen will make 2n revolution per second.
