Ultraviolet light of wavelength 350 nm and intensity `1 W//m^2` is directed at a potassium surface having work function 2.2 eV
(ii) if 0.5 percent of the incident photons produce photoelectric effect, how many photoelectrons per second are emitted from the potassium surface that has an area `1 cm^2`.
`E_("kmax") =1.3 eV, n= 8.8 xx 10^(11)("photo electron")/("second") or r =(Nhv)/t =nhv`