Question

In the photoelectric experiment apparatus containing the collector and the emitter plate, a saturated photoelectron current is observed. If an external electric field is applied in the direction opposite to the motion of the photoelectrons, what is the change observed in each of the following? Give reasons. 

i. The saturation value of the photocurrent 

ii. The kinetic energy of the photoelectrons striking the collector plate

Answer 1

i. The saturation value of the photo current remains constant. The rate at which the photoelectrons emitted per unit time remains unchanged.

ii. The kinetic energy of the photoelectrons increases due to electrostatic force experienced by the electric field applied in the direction opposite to their motion towards the collector plate.