EASY READ Electronics
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What is a light-emitting diode (LED)?
A light-emitting diode (LED) is an electronic component which lights up when an electric current flows through it. It is used in light bulbs, displays and many other devices. In electronics, it is often used as an indicator for whether the device is switched on.
How does an LED work?
An LED is a type of diode, a device that allows an electric current to flow through it in one direction but not the other. This means the LED will only work when its anode (its positively charged pin) is connected to the battery’s positive terminal.
An LED is made of a semiconductor material, which gives off light when an electric current passes through it. This effect is known as electroluminescence. Different materials produce light of different colours: red LEDs often contain aluminium gallium arsenide, while blue ones are usually based on zinc selenide.
No LED can produce white light directly from a single type of semiconductor, but blue LEDs can have a coating of chemical called a phosphor added to them. The phosphor absorbs some of the light and glows white.
Connecting an LED to a circuit
An LED has two pins: an anode and a cathode. The anode is the longer pin and it connects to the positive terminal of the battery. The cathode connects to the negative terminal. (If you connect them in the opposite direction, no current will flow). It is important to connect an LED in series with a resistor to limit its current. Too much current will cause the LED to heat up quickly and "blow".
To find out how to build a simple circuit with an LED, go to this page and watch the video in the How to build an electronic circuit section.
Consultant: Mike Goldsmith
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