Q. A plane electromagnetic wave of wave intensity $6\ W/m^{2}$ strikes a small mirror area $40\ cm^{2}$, held perpendicular to the approaching wave. The momentum transferred by the wave to the mirror each second will be
A) $6.4 \times 10^{- 7}kg - m/s^{2}$
B) $4.8 \times 10^{- 8}kg - m/s^{2}$
C) $3.2 \times 10^{- 9}kg - m/s^{2}$
D) $1.6 \times 10^{- 10}kg - m/s^{2}$
Explanation
(d) Momentum transferred in one second
$p = \frac{2U}{c} = \frac{2S_{av}A}{c} = \frac{2 \times 6 \times 40 \times 10^{- 4}}{3 \times 10^{8}}$
$= 1.6 \times 10^{- 10}kg - m/s^{2}$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.