When a monochromatic point source of light is at a distance
of 0.2 m from a photoelectric cell, the cut off voltage and the saturation current
are respectively 0.6 V and 18.0 mA. If the same source is placed 0.6 m away
from the photoelectric cell, then
(a) the stopping potential will be 0.2 V
(b) the stopping potential will be 0.6 V
(c ) the saturation current will be 6.0 mA
(d) the saturation current will be 2.0 mA

Options

A. the stopping potential will be `0.2V`
B. the stopping potential will be `0.6V`
C. the stopping potential will be `6.0V`
D. the stopping potential will be `2.0V`

Answer

B, D

Explanation

(b)Stopping potentail remains the same as it depends on the frequency of incident radiation.
(D)Saturation current `alpha` intensity of incident radiation `a1/r^(2)`.Since `r` becomes three times `((0.6m)/(0.2m))`,saturation current becomes `(18.0mA)/(3)^(2)=2.0mA`