The work function of a metal is 6.4x10-19J. If the metal is irradiated with radiation of wavelength 200nm,then the maximum K.E  of the photoelectrons would be about

Given, λ=200nm =200×10-9m           E=hCλ=6.6×10-34×3×1082×10-7=9.9×10-19J Work function,W=6.4×10-19J According to photoelectric effect, E=W+K.E   K.E=9.9×10-19-6.4×10-19=3.5×10-19J