What would be the ideal value of the work function of a material used to make a sensor that does not detect visible light, but only detects far ultraviolet light with a wavelength less than 200 nm? Such materials are used to make "solar blind" sensors. Give a value in electron volts (without the units) for the workfunction that would make a detector blind to any light of wavelength 380 nm or longer. We will check your answer to an accuaracy of 0.3 eV.