The ground state energy of hydrogen atom is -13.6 eV. The photon emitted during the transition …………….

Class 12th Physics, Question -The ground state energy of hydrogen atom is -13.6 eV. The photon emitted during the transition of electron from n=3 to n=1 state, is incident on a photosensitive material of unknown work function .The photoelectrons are emitted from the material with the maximum kinetic energy of 9eV.Calculate the threshold wavelength of the material used.