Light-Emitting Diodes Explained - LEDs

A light emitting diode (LED for short) is a diode that emits light. Light-emitting diodes have many applications, some functional and some decorative. But LEDs are simple electronic components and a basic understanding of their functionality can help you make the most of light emitting diodes.

A light emitting diode is a semiconductor component. In general, a diode is a device that allows electrical current to pass in one direction but blocks the flow of electrons in the reverse direction. A light-emitting diode is a diode that emits light at a specific frequency (depending on the exact composition of the diode). LEDs commonly are available in green, red, and amber, although blue and white LEDs have become more commonly available in recent years. There are even infrared LEDs for use in remote control devices that produce infrared light, invisible to the naked eye but detectable by an infrared detector.

To function properly, LEDs must be connected in a DC electrical circuit in the correct way. Since diodes allow current to flow only in one direction, reversing an LED from its proper orientation will break the electrical circuit and halt the flow of electrons. For now, just remember that an LED will only light up when connected in one direction, and no current will flow if the diode is reversed.

Light emitting diodes are useful for decoration, because they are small, colorful and consume little electricity. They can be powered by very small batteries as long as a current-limiting resistor is connected in series with the light emitting diode so that the LED doesn't serve as a short-circuit across the battery terminals. Some LEDs even have current-limiting resistors built inside.

Light emitting diodes have been used as indicator lights for decades, but they have recently begun being used in aggregate as alternatives to traditional incandescent bulbs due to their low energy consumption. Since LEDs are commonly available at RadioShack, they are often used by hobbyists in electronics projects and by students in science experiments. They have even been used to make colorful and safe Jack-o-Lanterns for Halloween decorations. The various uses for LEDs are limited only by your imagination. With a few LEDs, a battery, a resistor, and some wire, you can make homemade Christmas decorations or light displays.

In conclusion, light-emitting diodes are semiconductor devices that can be used in a host of practical and fun applications. They require very little power and are available in many colors. They function in a DC circuit in only one direction, and they require anywhere from 1.5 to 12 Volts, depending on the LED. They are a safe and educational way to experiment with electricity and electronic light sources.