The energy is calculated as: E=hcλ =6.6×10−34Js×
3×108m∕s
300×10−9m
=
1.98×10−25
300×10−9m
=6.6×10−19J The energy in eV is derived as: 1eV=1.602×10−19 Energy=
6.6×10−19
1.602×10−19
=4.119eV The metals which are having less value of work function than the energy calculated, they can undergo photoelectric effect. Therefore, metals are Mg,K and Na