The work function of very pure Na is 2.75 eV, where 1 eV = 1.602 x 10-19 J.
(a) Calculate the maximum kinetic energy of photoelectrons emitted from Na exposed to 200 nm ultraviolet radiations
(b) Calculate the longest wavelength that will cause the photoelectric effect in pure Na.
(c) The work function of sodium that has not been very carefully purified is substantially less than 2.75 eV, because of adsorbed sulfur and other substances derived from atmospheric gases. When impure Na is exposed to 200-nm radiation, will the maximum photoelectron kinetic energy be less than or greater than that for pure Na exposed to 200-nm radiation?