question_answer

It is difficult to eject out an electron from copper than sodium. Which of the two metals has greater work function and which has greater threshold wavelength?

Answer:

                Since electron ejection is difficult from copper than sodium, so copper has greater work function than sodium.                 Work function,  \[{{W}_{0}}=h{{\upsilon }_{0}}=\frac{hc}{{{\lambda }_{0}}}\] i.e., \[{{\lambda }_{0}}\propto \frac{1}{{{W}_{0}}}\]                 As threshold wavelength is inversely related with work function, so sodium has higher threshold wave- length than copper.