in a photo cell 4 unit photo electric current is flowing the distance between source and cathode is 4 unit . now the distance between source and cathode is 1 unit what will be photo electric current now

Dear Student,

The photoelectric current is directly proportional to the intensity of incident light. Also, the intensity of incident light is inversely proportional to the square of the distance of the source.
Since the distance is reduced by 4 times, the intensity will be increased by 4^2 = 16 times. Hence the photoelectric current will also be increased by 16 times.
So the new value of photoelectric current will be:

i = 4 X 16 = 64 units


  • 4
(1/4) times or quarter

  • -4
Intensity of photon (means no. Of photo electron emitted )
Intensity inversely propotional to square of distance. Which means on decreasing the distance increase the intensity.
Hence it will become 64
  • 3
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