Question

A radiation of $200\, W$ is incident on a surface which is $60 \%$ reflecting and $40 \%$ absorbing. The total force on the surface is

• A. $1.07 \times 10^{-6} N$
• B. $1.3 \times 10^{-6} N$
• C. $1.07 \times 10^{-7} N$
• D. $1.03 \times 10^{-7} N$

Answer 1

Answer: (A)

Here, $F_{\text {total }}=F_{\text {re }}+F_{a b s}$
$=\frac{1.2 P}{C}+\frac{0.4 P}{C}=\frac{1.6 P}{C}$
$=\frac{1.6 \times 200}{3 \times 10^{8}}=1.07 \times 10^{-6} N$