A lightemitting diode LED is a semiconductorlight source that emits light when current flows through it. Electrons in the semiconductor recombine with electron holes, releasing energy in the form of photons. The color of the light corresponding to the energy of the photons isdetermined by the energy required for electrons to cross the band gap of the semiconductor. White light is obtained by using multiple semiconductors or a layer of lightemitting phosphor on the semiconductor device. Specifications. Color Yellow. Voltage 24VDC. Height 1.25 in.. Width 6 in.. Length 4.1 in.