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8.Electromagnetic waves
easy
Electromagnetic wave of intensity $1400\, W/m^2$ falls on metal surface on area $1.5\, m^2$ is completely absorbed by it. Find out force exerted by beam
A
$14 \times 10^{-5} \, N$
B
$14 \times 10^{-6} \, N$
C
$7 \times 10^{-5} \, N$
D
$7 \times 10^{-6} \, N$
Solution
Pressure $=\frac{1}{c}$
$\therefore$ Force $=\frac{I}{c} \times A=\frac{1400}{3 \times 10^{8}} \times 1.5=7 \times 10^{-6} \mathrm{\,N}$
Standard 12
Physics