When a monochromatic point-source of light is at a distance of 0.2 m from a small photoelectric cell, the stopping potential 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 :-
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Question

When a monochromatic point-source of light is at a distance of 0.2 m from a small photoelectric cell, the stopping potential 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 :-

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G1 Physics · Accepted Answer

Step 1: For the same monochromatic source, photon energy and hence stopping potential do not depend on distance. Step 2: Intensity varies as 1/r², so the photoelectron rate and saturation current vary as 1/r². Step 3: Apply the given distance ratio and compare with the options. Final: D: The saturation current will be 2.0 mA.