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8.Electromagnetic waves
medium
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
$1.6 \times {10^{ - 10}}kg - m/{s^2}$
Solution
(d)Momentum transferred in one second
$p = \frac{{2U}}{c} = \frac{{2{S_{av}}A}}{c} = \frac{{2 \times 6 \times 40 \times {{10}^{ – 4}}}}{{3 \times {{10}^8}}}$
$=$$1.6 \times {10^{ – 10}}kg – m/{s^2}$
Standard 12
Physics
