Three identical photoelectric cells A, B and C are irradiated separately by the same…
PHYSICS · Multi-part · A Level · Physics · Particles and radiation · Particles and radiation
Problem
Three identical photoelectric cells A, B and C are irradiated separately by the same monochromatic light of frequency ν (greater than the threshold frequency of the metal). The incident intensities on the three cells are I,2I and 3I respectively.
(i) On a common set of axes sketch the expected photocurrent versus applied voltage curves for the three cells, clearly labelling the curves for A, B and C.
(ii) Using the photon picture of light, explain the differences observed in the saturation currents and in the stopping potentials of the three curves.
(iii) If the saturation current for cell B is 24μA, calculate the saturation currents for cells A and C.
(iv) Describe qualitatively how all three curves would be affected if the frequency of the incident light is decreased (but kept above the threshold value) while the intensities remain the same.