Red LED Flashlight

LED is short for light-emitting diode. They are a semiconductor light source that are used as an indicator for a lot of different devices. In a nutshell, when the diode is turned on, the electrons are stimulated and reconnect with holes that are in the device, which releases photon energy. The effect that is produced is called electroluminescence. The color that the diode emits is determined by the energy gap of the semiconductor. The LED bulbs are small, measuring to be less than 1mm(squared).

So what is a diode?

The diode is a very simple semiconductor. Now what is a semiconductor? A semiconductor is a material with different abilities to conduct electrical current. In order to create light, there needs to either be extra holes or extra electrons. In completely pure material, there is a perfect balance between the holes and electrons, leaving no free holes or electrons.

A semiconductor with extra electrons is called N-type and a semiconductor with extra holes is called P-type. Running a current through the semiconductor, the electrons and holes interact with each other, and the resulting product is light!

Why is Light Produced?

The way light works is, photons are released when electrons move from one orbital to another. Electrons with greater energy move in orbitals that are further away from the center of the atom (nucleus). As the electron moves from a higher orbital to a lower orbital, it must release energy. This resulting energy is released as light.