If light of wavelength of maximum intensity emitted from surface at temperature `T_(1)` Is used to cause photoelectric emission from a metallic surface, the maximum kinetic energy of the amitted electron is 6 ev, which is 3 time the work function of the metallic surface. If light of wavelength of maximum intensity emitted from a surface at temperature `T_(2) (T_(2)=2T_(1))` is used, the maximum kinetic energy of the photoelectrons emitted is