In a photoelectric cell,the conversion of energy takes place from:

When the distance of a light source from a photocell is $r_1$,the photoelectric current is $I_1$. If the distance is $r_2$,the photoelectric current becomes $I_2$. The ratio $(I_1 : I_2)$ is .....

When yellow light is incident on a surface,no electrons are emitted,while green light can emit them. If red light is incident on the surface,then:

For alkali metals, threshold frequencies lie in which region?

$A$ point source causes the photoelectric effect from a small metal plate. Which of the following curves may represent the saturation photocurrent $(I)$ as a function of the distance $(r)$ between the source and the metal?

In a photoelectric experiment,if the intensity of incident light is doubled and the frequency is kept slightly greater than threshold frequency,then the saturation photoelectric current