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Question
On the basis of the graphs shown in the figure, answer the following questions :
(a) Which physical parameter is kept constant for the three curves?
(b) Which is the highest frequency among v1, v2, and v3?
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Solution
(a) Intensity is kept constant for all three curves. The given graph shows the variation of photocurrent with collector plate potential for the same intensity of light radiation at various frequencies.
(b) The stopping potential is found to be changing linearly with the frequency of incident light. The stopping potential is more negative for higher frequencies of incident radiation. As an increase in the frequency of the incident light increases the kinetic energy of the emitted electrons, so the greater retarding potential is required to stop them completely.
Hence higher the negative potential, the more the frequency of incident electrons.
As V1 is more negative than V2 and V2 is more negative than V3, hence, V1 > V2 > V3
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