When a monochromatic point source of light is at a distance 0.2 m from a photoelectric cell, the saturation current and cut-off voltage are 12.0 mA and 0.5 V. If the same source is placed 0.4 m away from the photoelectric cell, then the saturation current and the stopping potential respectively are

Options

A. 4mA and 1V
B. 12mA and 1V
C. 3mA and 0.5V
D. 12mA and 0.5V

Answer

C

Explanation

`I prop1/(("distance")^2)implies I_1/I_2 = (d_2/d_1)^(2)=((0.4)/(0.2))^(2)`
`implies I_2=3mA`
Stopping potential is independent of distance.