Photo cells convert

How many times more photons are emitted from a photocell by a source placed at a distance of $1 \ m$ compared to a source placed at a distance of $2 \ m$?

The quantum nature of light is explained by which of the following phenomena?

$A$ photocell is illuminated by a small bright source placed $d \; m$ away. When the same source of light is placed $\frac{d}{2} \; m$ away,the number of electrons emitted by the photocathode would

The maximum value of the stopping potential in the following diagram is .......... $V$.

The distance between a light source and a photoelectric cell is $d$. If the distance is decreased to $\frac{d}{2}$,then: