An LED is useful because when a current passes through it, it gives out light (specifically photons of visible or sometimes infrared light).

Quick scoop

  • LED stands for light-emitting diode, which is a special semiconductor component.
  • When it is forward biased and current flows, electrons and holes recombine in the junction.
  • The recombination releases energy as photons, so the LED gives out light rather than mainly heat like an ordinary diode.

So the one-word answer to “it gives out… what?” is: light (or “photons of light”).

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