49) If the work function of a material is 2eV, then minimum frequency of light required to emit photo-electrons is

50) If the threshold wavelength of radiations required to eject a photoelectron from a metal surface is 6??10^?7?m, then work function of the metal is

51) If work function of a metal surface is 3.45 eV ,then maximum wavelength of a photon required to eject a photoelectron is

52) Threshold frequency of a photon required to eject a photoelectron from the surface of cesium is

53) If work function of a metal plate is negligible then the K.E.of the photoelectrons emitted when radiations of 1000?A⁰?are incident on the metal surface is