Two photoelectric cells are identical except for the metal that forms the emitting surface
PHYSICS · Multi-part · CBSE · Physics · Dual Nature of Radiation and Matter · Dual Nature of Radiation and Matter
Problem
Two photoelectric cells are identical except for the metal that forms the emitting surface. Cell A uses metal X, whose work function is greater than that of metal Y used in cell B. Both cells are simultaneously illuminated by the same monochromatic light source of frequency well above the threshold of each metal. A variable potential difference is applied between the emitter and collector of each cell so that the measured photocurrent just reaches zero (the stopping condition).
(a) Indicate which cell—A or B—requires the larger magnitude of applied potential difference to reach the stopping condition.
(b) Explain in detail why the difference in work function leads to the result identified in part (a). In your explanation, refer to the relative photon energies, electron kinetic energies, and the role of the external potential difference.
(c) Suppose the frequency of the incident light is increased while its intensity remains constant. Describe qualitatively how the required stopping potential for each cell would change, if at all, and justify your answer.