Question
A sheet of silver is illuminated by monochromatic ultraviolet radiation of wavelength 1810 Å. What is the maximum energy of the emitted electrons? The threshold wavelength for silver is 2640 Å.

2.60 eV

2.71 eV

2.16 eV

None of these
diffcult
Solution
2.16 eV
If v be the frequency of radiation illuminating the surface and v_{0} the threshold frequency, then according to Einstein’s photoelectric equation, the maximum kinetic energy of the emitted electrons is
.
If be the wavelength of the incident light and , the threshold wavelength, then
Substituting the given values of h, c and . We have
.
= 2.16 eV.
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