Mohan thought that there are materials which absorb photons of shorter wavelength and emit photons of longer wavelength. But, can there be stable substances which absorb photons of larger wavelength and emit light of shorter wavelength? He got confused and could not find its answer. Then he requested his friend Sohan. Sohan explained him that in the first case, energy given out is less than the energy supplied. But in the second case, the material has to supply the energy as the emitted photon has more energy, which cannot happen for stable substances.
(a) What values do you notice in Sohan ?
(b) Consider a metal exposed to light of wavelength 600 nm. The maximum energy of the electron doubles when light of wavelength 400 nm is used. Find the work function in eV.