The cathode of a photoelectric cell is changed so that its work function changes from W₁ to W₂ (W₂ > W₁). If photocurrents before and after are I₁ and I₂ under identical illumination with hν > W₂, what relation holds?
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Question

The cathode of a photoelectric cell is changed so that its work function changes from W₁ to W₂ (W₂ > W₁). If photocurrents before and after are I₁ and I₂ under identical illumination with hν > W₂, what relation holds?

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G1 Physics · Accepted Answer

Assume the same illumination intensity and identical electron collection efficiency, with photon energy hν exceeding both work functions. The incident photon flux is unchanged. In the ideal photoelectric model the saturation photocurrent depends on photon flux, whereas the stopping potential changes with work function. Hence I₁ = I₂. Answer: A.