On a photosensitive material, when frequency of incident radiation is increased by 20 % , maximum kinetic energy of emitted photoelectrons increases from 0.4 eV to 0.7 eV . The work function of the material is

Step-by-step solution

Einstein's photoelectric equation is KE_ = hf - , where KE_ represents the maximum kinetic energy of emitted photoelectrons, h is Planck's constant, f denotes the frequency of incident radiation, and is the material's work function. Given: Initial kinetic energy KE₁ = 0.4 eV at frequency f₁ , yielding: 0.4 = hf₁ - When frequency increases by 20% to 1.2f₁ , the new kinetic energy becomes KE₂ = 0.7 eV : 0.7 = 1.2hf₁ - Substituting hf₁ = 0.4 + from the first equation into the second: 0.7 = 1.2(0.4 + ) - 0.7 = 0.48 + 0