Effect of Distance on Photocell Current – Rankers Physics
Topic: Modern Physics
Subtopic: Photoelectric Effects and deBroglie Equation

Effect of Distance on Photocell Current

Photocell is illuminated by a point source of light, which is placed at a distance \(d\) from the cell. If the distance becomes \(2d\), then number of electrons emitted per second will be
Remain same
Four times
Two times
One-fourth

Solution:

Intensity of light from a point source is inversely proportional to the square of the distance, \(I \propto \frac{1}{d^2}\). Since the number of photoelectrons emitted per second is proportional to intensity, doubling the distance reduces the emission to one-fourth.

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