Wavelength ? = 400 nm = 400*10^-9 m = 4*10^-7 m
Energy of photon E = hc/? = (6.63*10^-34*3*10^8)/(4*10^-7)
                                     Â
= 4.972*10^-19 J = (4.972*10^-19)/(1.602*10^-19)
                                                              Â
= 3.103 eV
Maximum kinetic energy Ko = 1.10 eV
Work function of the metal surface W = E - Ko = 3.103 - 1.10 =
2.003 eV
New wavelength ?' = 320 nm = 320*10^-9 m
Energy of the incident photon E' = 6.416*10^-19 J = 4.004 eV
Maximium Kinetic energy Ko' = E' - W
                                        Â
= 4.004 - 2.003 = 2.001 eV = 3.205*10^-19 J
