Question

Find the maximum kinetic energy of photoelectrons liberated from the surface of lithium by electromagnetic radiation whose electric component varies with time as E = a (1 + cos ωt) cos ω₀t, where a is a constant, ω = 6.0.10¹⁴ s^-1 and ω₀ = 3.60.10¹⁵s^-1 .

Answer 1

We write

It is obvious that light has three frequencies and the maximum K.E. of photo electrons ejected is

where A_Li = 2.39 eV . Substituting we get 0.37 eV.