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 0.2 V
B. The stopping potential will be 0.6 V
C. Thte saturation current will be 6 mA
D. The saturation current will be 18 mA

Explanation

Cut off voltage is independent of intensity and hence remains the same.
distance becomes 3 times, so intensity (I) becomes `(I)/(9)`. Hence photo current also decreases by this factor i.e. becomes `(18)/(9) = 2mA.`