Question

The pressure exerted by an electromagnetic wave of intensity $I\left( watt / m ^{2}\right)$ on a non-reflecting surface is [c is the velocity of light]

• A. $Ic$
• B. $I c^{2}$
• C. $\frac{I}{c}$
• D. $\frac{I}{c^{2}}$

Answer 1

Answer: (C)

Pressure $=$ Force/area
$I=\frac{\text { Energy }}{\text { area }-\text { time }}=\frac{F . S}{A t}=\frac{F_{C}}{A} .$ or $I / c=P$.