(a) Photoelectrons with a maximum kinetic energy of 7.95 eV are emitted from a metal when it is illuminated by ultraviolet radiation with a wavelength of 1.25 10-7 m. (i) Calculate the energy of the incident photons in electronvolts. (ii) Calculate the wavelength of the radiation (in nanometres) corresponding to the lowest energy photons that can free electrons from the metal. (iii) How do you explain the fact that, when infrared radiation is shone on this metal, no photoelectrons are emitted? (b) What is the de Broglie wavelength (in nanometres) of an electron with a kinetic energy of 7.95 eV?