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

$A$ convex lens of focal length $40 \ cm$ forms an image of an extended source of light on a photoelectric cell. $A$ current $I$ is produced. The lens is replaced by another convex lens having the same diameter but focal length $20 \ cm$. The photoelectric current now is:

$A$ small metal ball is suspended in a uniform electric field with the help of an insulated thread. If a high energy $X-$ray beam falls on the ball,then the ball

The cathode of a photocell is changed such that the work function changes from $w_1$ to $w_2$ $(w_2 > w_1)$. If the saturation currents before and after the change are $I_1$ and $I_2$ respectively,and all other conditions (such as incident light intensity and frequency) remain unchanged,then (assuming $h\nu > w_2$):

In the photoelectric effect,a photocell is used for the conversion of ..........

Explain the effect of variation of intensity of incident radiation on photoelectric current.