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Question
The photoelectric threshold wavelength of a metal is 230 nm. Determine the maximum kinetic energy in joule and in eV of the ejects electron for the metal surface when it is exposed to a radiation of wavelength 180 nm.
[Planck’s constant : h = 6.63 * 10-34 Js, Velocity of light : C = 3 * 108 m/s.]
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Solution
λ0 = 230 nm = 230 × 10−9m,
λ = 180 nm = 180 × 10−9m,
h = 6.63 × 10−34 J s, c = 3 × 108
m/s, K.E. (in joule and eV) = ?
Now,
∴ The maximum kinetic energy of the ejected electron is 2.402 × 10−19 J.
∴ The maximum kinetic energy of the ejected electron is 1.5 eV.
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