Photoelectric emission occurs only when the incident light has more than a certain minimum

In the Davisson and Germer experiment, the velocity of electrons emitted from the electron gun can be increased by

Light of two different frequencies whose photons have energies 1 eV and 2.5 eV respectively illuminate a metallic surface whose work function is 0.5 eV successively. Ratio of maximum speeds of emitted electrons will be

In photoelectric emission process from a metal of work function 1.8 eV, the kinetic energy of most energetic electrons is 0.5 eV. The corresponding stopping potential is