Experimental facts on photoelectric effects 1.Electrons will be emitted when the plate is imposed in radiation. 2.electron will emitted only if the frequency of the radiation is high enough. 3.the time delay between the arrival of radiation and the appearance of photoelectron is not measurable. 4.The magnitude of current is determined by the intensity of incident rays.Experimental facts on photoelectric effects 1. Electrons will be emitted when the plate is imposed in radiation. 2.electron will emitted only if the frequency of the radiation is high enough. 3.the time delay between the arrival of radiation and the appearance of photoelectron is not measurable. 4. The magnitude of current is determined by the intensity of incident rays