Question

A photoelectric cell is illuminated by a point source of light 1 m away. When the source is shifted to 2 m then

• A. each emitted electron carries one quarter of the initial energy
• B. number of electrons emitted is half the initial number
• C. each emitted electron carries half the initial energy
• D. number of electrons emitted is a quarter of the initial number

Answer 1

Answer: (D)

number of electrons emitted is a quarter of the initial number

photoelectric current $I\propto$ intensity of light and
For opint source:

$Intensity\propto \frac{1}{(distance{)}^2}$

$\therefore I\propto \frac{1}{(distance{)}^2}$