Question

If the distance of $100W$ lamp is increased from a photocell, the saturation current $i$ in the photocell varies with the distance $d$ as

• A. $i\propto d^2$
• B. $i\propto d$
• C. $i\propto \frac{1}{d}$
• D. $i\propto \frac{1}{d^2}$

Answer 1

The correct option is D $i\propto \frac{1}{d^2}$

As we know, Photoelectric current depends on the intensity of incident radiation i.e., $i\propto I$
But, intensity of radiation $I\propto \frac{1}{d^2}$ so, $i\propto \frac{1}{d^2}$