When you interchange your emitter for one with a smaller work function, you measure

A. An increased current
B. A decrease in the necessary stopping voltage
C. An increase in the necessary stopping voltage
D. No change in either current or stopping voltage
E. Either a or c. You cannot determine which from the information given.


C.
Any changes in stopping voltage would change the necessary energy to bridge the emitter-collector gap. Since a current i is already established, the electrons could already get across, and with a decreased work function, the photons are greater in energy. An increase in the necessary stopping voltage would mean that just the most energetic electrons will bridge the gap

Physics & Space Science

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