Answer:
1.41eV
Explanation:
Kinetic Energy of photoelectron(K. Emax)
E = Wo + K.Emax
E = hc/ λ
h = planck's constant = 6.63 * 10^-34
c = speed of light = 3×10^8 m/s
λ = 400nm
Work function (Wo) = 1.70eV
1 eV = 1×10^-19
E = [(6.63×10^-34) * (3×10^8)] / 400×10^-7
E = (19.89 × 10^(-26))/400×10^-7
E = 0.049725×10^-19
K.Emax = E - Wo
K.Emax = (0.049725×10^-19) - (1.7×10^-38)
0.049725×10^-19 interms of eV = (0.049725/1.6)×10^-19 =
K.Emax = 3.11eV - 1.70eV
K.Emax = 1.41eV
