Q. A photocell is illuminated by a small bright source placed $1\ m$ away. When the same source of light is placed $1/2\ m$ away, the number of electrons emitted by photo cathode would
A) Decrease by a factor of 2
B) Increase by a factor of 2
C) Decrease by a factor of 4
D) Increase by a factor of 4
Explanation
(d) Number of photoelectrons $\propto \frac{1}{(Distance)^{2}}$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.