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How Does an LED Emit Light?

Light-emitting diodes, or LEDs, are used where a low-energy, long-lasting light is required. A LED will emit light that is not an adequate source of light for some applications, like indoor plant growing, as they lack the range of color in the light spectrum that is needed. The lower power needs of an LED make them a common choice for electronic indicator lights because their power draw will not interfere with the overall power supply.

Conductive Crystals
- LEDs emit light due to the transmission of electrons from a high-energy (n-type) conductive crystal to a low-eneregy (p-type) crystals. When power is applied, the electrons in the high-energy crystal moved faster and cross over to the low-energy crystal. There the electrons assume the behavior of low-energy movement. When the n-type loses its energy and falls to a p-type level, light is emitted.
Diode
- The diode used with an LED light consists of a positive and negative wire connected to the set of n- and p-type conductive crystals. The positive wire is connected to an energy source and the negative wire acts as the ground. The transmission process between the crystals that generate light occurs in the body of the diode between the two wires. A bulb may be attached to the body to amplify the light.
Connection
- LED wires must be attached to the appropriate power and ground sources. Each wire is marked, typically on the body of the diode, with an indication of whether it is positive or negative. Alternately, the diode may have one arrow printed on it, with the direction of the arrow indicating the direction electricity should be flowing toward.
Lens
- The lens attached to the diode body on an LED is what provides both color and amplification to the light produced. A visible LED produces a white light, although there are different types of LEDs that can produce other colors.

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