InterviewSolution
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InterviewSolution
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When a monochromatic point source of light is at a distance of `0.2` m from a photoelectron cell the cut off voltage and the saturation currect are respectively `0.6V` and `18.0 mA` if the same is plased `0.6 m` away from the photoelectric cell , thenA. the stopping potential will be `0.2Volt`B. the stopping potential will be `0.6 Volt`C. the stopping potential will be `6.0 Volt`D. the stopping potential will be `2.0 Volt` |
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Answer» Correct Answer - B::D Since the stopping potential depands on the frequency and not on the intensity and the source is same , the stopping potential remain unaffected . The sqatutation currect depends on the intensity of incident light on the cuthode of the photocell which in turn depends on the distance of the source from the cathode the intensity (i() of lioght is inversely propotional to the square of the distance between the light source and photcell `1 prop (1)/(r^(2))` and saturation currect `prop 1` `rArr Saturation Currect prop (1)/(r^(2))` `rArr ((Sataration Currect)_(fanal)/((Sataration Currect) _(mital) = (r_(initial)^(2))/(r_(final)^(2))` `rArr (Saturation Currect)_(final) = (0.2 xx 0.2)/(0.6 xx 0.6) xx 18 = 2mA` |
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