Question

An electromagnetic wave with intensity vector 6 watt $/ m ^{2}$ is absorbed by a surface of area $12 m ^{2}$. Find the force on the surface?

• A. $24 N$
• B. $24 \times 10^{10} N$
• C. $24 \times 10^{-10} N$
• D. $24 \times 10^{-8} N$

Answer 1

Answer: (D)

$F = PA : P =\frac{ I }{ c }$
$\therefore F=\frac{I A}{c}=\frac{6 \times 12}{3 \times 10^{8}}$
$=24 \times 10^{-8}\, N$