1.

A photon of energy 40 eV is incident on a surface of metal. Due to this an electron is emitted of kinetic energy 37.5 eV. Find out the work function of the metal:(a) 2.5 eV(b) 57.5 eV(c) 5.0 eV(d) zero

Answer»

(a) 2.5 eV
From Einstein photoelectric equation
hv = ϕ + EK
40 eV = ϕ + 37.5 eV
ϕ = (40 – 37.5) eV
= 2.5 eV



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