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How does an LED work?

Light-emitting diodes – commonly called LEDs– are found in several your MakeCrate projects. They come in a range of colors, sizes, and intensities. Our directions and videos emphasize that the LEDs must always be connected in the correct direction, and if you reverse one in a circuit, you’ll see that it no longer works. Let’s look at what is going on inside and LED that makes it work like that.

First, we’ll start with some vocabulary.

A diode is an electrical device that allows for the current to move through it in one direction.

A semiconductor is a material that allows electricity to pass through it partly. This is different than a conductor, which allows electricity to flow freely, and aninsulator, which allows almost no electricity to pass through.

So, an LED is a diode that contains two types of semiconductor material inside. On one side, there is p-type material, which contains positively charged particles called “holes”. On the other side, there isn-type material, which contains extra electrons, which are negatively charged.

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When an LED is inserted into a circuit, it must be done so that the side containing the n-type material is on the negative side of the circuit while the p-type material must be on the positive side.

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When electric current flows through the circuit, the electrons from the n-type material and the holes from the p-type material can move towards the other side of the material.

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Once the holes and electrons are in motion, they begin to interact, and this interaction causes the release of energy as photons, which we see as light.

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The types of material in the semiconductor determine what color light the LED emits.

Got questions? Post them in the comments below.

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