Led how does it work

An electrical current passes through a microchip, which illuminates the tiny light sources we call LEDs and the result is visible light. To prevent performance issues, the heat LEDs produce is absorbed into a heat sink. The useful life of LED lighting products is defined differently than that of other light sources, such as incandescent or compact fluorescent lighting CFL. LEDs are incorporated into bulbs and fixtures for general lighting applications.

Small in size, LEDs provide unique design opportunities. Some LED bulb solutions may physically resemble familiar light bulbs and better match the appearance of traditional light bulbs. LEDs offer a tremendous opportunity for innovation in lighting form factors and fit a wider breadth of applications than traditional lighting technologies. LEDs use heat sinks to absorb the heat produced by the LED and dissipate it into the surrounding environment.

This keeps LEDs from overheating and burning out. What is an LED? Indicator — an inexpensive, low-power device that is used as indicator lights in cars, panels, and other electronic devices. Illuminator — a high-power device that provides illumination. These are the type of LEDs you buy to illuminate rooms in your home or office. They can be found in a variety of styles, shapes and colours suitable for almost any application.

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Sign in close. Lost your password? Remember me. In other words, one LED bulb can last as long as 21 watt incandescent bulbs burned consecutively [source: EarthEasy ]. Until recently, LEDs were too expensive to use for most lighting applications because they're built around advanced semiconductor material.

The price of semiconductor devices plummeted after the year , however, making LEDs a more cost-effective lighting option for a wide range of situations.

Several companies have begun selling LED light bulbs designed to compete with incandescent and compact fluorescents that promise to deliver long lives of bright light and amazing energy efficiency. In this article, we'll examine the technology behind these ubiquitous blinkers, illuminating some cool principles of electricity and light in the process.

A diode is the simplest sort of semiconductor device. Broadly speaking, a semiconductor is a material with a varying ability to conduct electrical current. Most semiconductors are made of a poor conductor that has had impurities atoms of another material added to it. The process of adding impurities is called doping. In pure aluminum-gallium-arsenide, all of the atoms bond perfectly with their neighbors, leaving no free electrons negatively charged particles to conduct electric current.

In doped material, additional atoms change the balance, either adding free electrons or creating holes where electrons can go. Either of these alterations make the material more conductive. A semiconductor with extra electrons is called N-type material , since it has extra negatively charged particles. In N-type material, free electrons move from a negatively charged area to a positively charged area.

A semiconductor with extra holes is called P-type material , since it effectively has extra positively charged particles. Electrons can jump from hole to hole, moving from a negatively charged area to a positively charged area. As a result, the holes themselves appear to move from a positively charged area to a negatively charged area. A diode consists of a section of N-type material bonded to a section of P-type material, with electrodes on each end.

This arrangement conducts electricity in only one direction. When no voltage is applied to the diode, electrons from the N-type material fill holes from the P-type material along the junction between the layers, forming a depletion zone.

In a depletion zone , the semiconductor material is returned to its original insulating state — all of the holes are filled, so there are no free electrons or empty spaces for electrons, and electricity can't flow.

To get rid of the depletion zone, you have to get electrons moving from the N-type area to the P-type area and holes moving in the reverse direction. To do this, you connect the N-type side of the diode to the negative end of a circuit and the P-type side to the positive end.

The free electrons in the N-type material are repelled by the negative electrode and drawn to the positive electrode. The holes in the P-type material move the other way.

When the voltage difference between the electrodes is high enough, the electrons in the depletion zone are boosted out of their holes and begin moving freely again. The depletion zone disappears, and charge moves across the diode.

If you try to run current the other way, with the P-type side connected to the negative end of the circuit and the N-type side connected to the positive end, current will not flow.

The negative electrons in the N-type material are attracted to the positive electrode. The positive holes in the P-type material are attracted to the negative electrode. No current flows across the junction because the holes and the electrons are each moving in the wrong direction.

The depletion zone increases. See How Semiconductors Work for more information on the entire process. The interaction between electrons and holes in this setup has an interesting side effect — it generates light! Light is a form of energy that can be released by an atom. It's made up of many small particle-like packets that have energy and momentum but no mass.

These particles, called photons , are the most basic units of light. Photons are released as a result of moving electrons. In an atom, electrons move in orbitals around the nucleus. Electrons in different orbitals have different amounts of energy.

Generally speaking, electrons with greater energy move in orbitals farther away from the nucleus. For an electron to jump from a lower orbital to a higher orbital, something has to boost its energy level. Conversely, an electron releases energy when it drops from a higher orbital to a lower one.

This energy is released in the form of a photon. A greater energy drop releases a higher-energy photon, which is characterized by a higher frequency. As we saw earlier, free electrons moving across a diode can fall into empty holes from the P-type layer. This involves a drop from the conduction band to a lower orbital, so the electrons release energy in the form of photons.

This happens in any diode, but you can only see the photons when the diode is composed of certain material. The atoms in a standard silicon diode, for example, are arranged in such a way that the electron drops a relatively short distance.

As a result, the photon's frequency is so low that it's invisible to the human eye — it's in the infrared portion of the light spectrum.

This isn't necessarily a bad thing, of course: Infrared LEDs are ideal for remote controls , among other things.