Matter & Atoms

The surface of a metal is illuminated with the light of 400 nm. The kinetic energy of the ejected photoelectrons was found to be 1.68 eV. The work function of the metal is (hc = 1240 eV.nm)

  1. 1.41 eV
  2. 1.51 eV
  3. 1.68 eV
  4. 3.09 eV

Answer

hc/λ = φ + (K.E.)max

1240/400 = φ + 1.68

φ = 1.41 eV

The correct option is A.