Final answer:
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 will be 4πnR.
Step-by-step explanation:
The speed of light after reflection from the mirror can be determined using the following steps:
- When a ray of light falls on a small plane mirror placed at the center of a spherical screen, it is reflected back in the opposite direction.
- Since the mirror makes n revolutions per second, the light ray will be reflected n times per second.
- The speed of light on the screen after reflection from the mirror will be n times the distance traveled by the light ray in one revolution. Considering the circumference of the mirror as 2πR, where R is the radius of the spherical screen, the speed of light on the screen after reflection will be given by 2πnR.
Therefore, the correct answer is A. 4πnR.