The work function for sodium surface is 2.0eV and that for alluminium surface is 4.2eV. The two metals are illuminated with appropriate radiations so as to cause proto emission. Then

Options

A. the threshold frequency for sodium will be less than that for aluminium
B. the threshold frequency of sodium will be more than that of aluminium
C. both sodium and aluminium will have the same threshold frequency
D. none of the above

Answer

A

Explanation

As work function `W=hv_0`, where `v_0` is the threshold frequency. Greater the work function, greater is the threshold frequency. Therefore, the threshold frequency of sodium will be lesser than that for aluminium.