Q. A lasser beam is sent to the moon and reflected back to earth by ay mirror placed on the moon by an astronaut. If the moon is 384000 km from earth, how long does it take the light to make the round trip?
A) 5 min
B) 2.5 min
C) 2.5 s
D) 500 s
Explanation
(c) $t = \frac{2s}{c} = \frac{2 \times 38400 \times 1000}{3 \times 10^{8}} = 2.5\ s$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.