Em Waves Question 83
Question: A plane em wave of wave intensity of $ 10,W/m^{2} $ strikes a small mirror of area 20 $ cm^{2} $ , held perpendicular to the approaching wave. The radiation force on the mirror will be
Options:
A) $ 6.6\times {{10}^{-11}}N $
B) $ 1.33\times {{10}^{-11}}N $
C) $ 1.33\times {{10}^{-10}}N $
D) $ 6.6\times {{10}^{-10}}N $
Show Answer
Answer:
Correct Answer: C
Solution:
[c] Radiation force = Momentum transferred per second by electromagnetic wave to the mirror $ =\frac{2I _{av}A}{c}=\frac{2\times (10)\times (20\times {{10}^{-4}})}{(3\times 10^{8})}=1.33\times {{10}^{-10}}N $
BETA
