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
$I=\frac{\text{ Energy }}{\text{ area }-\text{ time }}=\frac{F.S}{At}=\frac{F_C}{A}.$ or $I/c=P$.