Optics Question 182
Question: A plane electromagnetic wave of wave intensity 6 W/m2 strikes a small mirror area 40 cm2, held perpendicular to the approaching wave. The momentum transferred by the wave to the mirror each second will be
Options:
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} $
Show Answer
Answer:
Correct Answer: D
Solution:
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/s2.
