A small source placed 1 m away from a photocell.It is illuminated by source. When the same source of light is placed `1/3 m` away, the number of electrons emitted by photo cathode would increase by a factor of --------

Explanation

To solve the problem, we need to understand how the intensity of light affects the number of electrons emitted by the photocell. The intensity of light is inversely proportional to the square of the distance from the source, according to the inverse square law.

### Step-by-Step Solution:

1. **Understanding the Inverse Square Law**:
The intensity \( I \) of light from a point source is given by:
\[
I \propto \frac{1}{d^2}
...