Question

Radiation of intensity $0.5W/m^2$ are striking a metal plate. The pressure on the plate is :

• A. $0.166\times {10}^{-8}N/m^2$
• B. $0.332\times {10}^{-8}N/m^2$
• C. $0.111\times {10}^{-8}N/m^2$
• D. $0.083\times {10}^{-8}N/m^2$

Answer 1

The correct option is A $0.166\times {10}^{-8}N/m^2$

Intensity or power per unit area of the radiation $P=fv\Rightarrow$

$f=\frac{P}{v}=\frac{0.5}{3\times {10}^8}=0.166\times {10}^{-8}N/m^2$

Where f is the force per unit area = pressure