A freshly prepared nickel surface (work function (5.0

PHYSICS · Multi-part · A Level · Physics · Particles and radiation · Particles and radiation

Problem

A freshly prepared nickel surface (work function 5.0 eV5.0\,\text{eV}) is illuminated with ultraviolet radiation of wavelength 200 nm.200\,\text{nm}. The emitted electrons are allowed to move towards a collector that is maintained at a positive potential of +2.0 V+2.0\,\text{V} with respect to the nickel surface. Take h=6.63×10−34 J s,  c=3.0×108 m s−1h=6.63\times10^{-34}\,\text{J\,s},\; c=3.0\times10^{8}\,\text{m\,s}^{-1} and e=1.6×10−19 C.e=1.6\times10^{-19}\,\text{C}. (a) Calculate the stopping potential that would have been required to bring the photocurrent to zero had the collector been at zero potential. (b) Determine the maximum kinetic energy (in eV\text{eV}) of the electrons reaching the collector when it is at +2.0 V.+2.0\,\text{V}. (c) If the collector potential is now reversed to −3.0 V-3.0\,\text{V} (i.e., retarding with respect to the emitter), will any photocurrent be observed? Justify your answer with suitable calculation.

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