Photons of wavelength 320 nm320\text{ nm}320 nm are incident on a metal plate. The work function of the metal is 3.2 eV3.2\text{ eV}3.2 eV. What is the maximum kinetic energy of the emitted electrons?
0.68 eV0.68\text{ eV}0.68 eV
3.9 eV3.9\text{ eV}3.9 eV
6.2 eV6.2\text{ eV}6.2 eV
7.1 eV7.1\text{ eV}7.1 eV
