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Question
Calculate the maximum kinetic energy of photoelectrons emitted by a metal (work function = 1.5 eV) when it is illuminated with light of wavelength 198 nm.
Solution
According to Einstein's photoelectric equation,
`"E"_k = hv - w = (hc)/lambda - w`
Here h = 6.6 × 10-34 Js
c = 3.0 × 108 ms-1
λ = 198 × 10-9 m
w = 1.5 × 1.6 × 10-19 J
`therefore "E"_k = ((6.6 xx 10^-34 xx 3.0 xx 10^8)/(198 xx 10^-9) - 1.5 xx 1.6 xx 10^-19)`J
= (10 × 10-19 - 2.4 × 10-19) J
= 7.6 × 10-19 J
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