A photocell is illuminated by a point source of light, which is placed at a distance d from the cell. If the distance becomes d 2 , then number of electrons emitted per second will

Step-by-step solution

The number of electrons emitted per second is known as the intensity of the light. Intensity is given by, I = E 4 π r 2 t , where E is the energy of the source, r is the distance and t is the time. We can see that the intensity of the incident light is inversely proportional to the square of the distance. When r = d , I 1 = E 4 π d 2 t . When r = d 2 , I 2 = E 4 π d 2 2 t . We have I 2 = 4 I 1 . Therefore, intensity becomes four times which means the number of electrons will become four times.