Light-emitting diodes (LEDs) #

A light-emitting diode is a piece of silicon that blocks current flow in one direction, but when current flows in the other direction, light comes out. I could try to write something hand-wavy about bandgaps here, but the truth is that they’re like magic to me.

When you include an LED in a circuit, typically you’ll want to include a resistor to limit the current drawn by the LED.

5 mm LED innards