LED Lighting

Incandescence

The emission of light by a hot object due to its temperature

Tungsten Filament

The thin resistor-like wire in an incandescent bulb that glows when heated by current.

2%

Only about __ of the input electrical energy is converted into visible light

Fluorescence

Emission of radiation by a material after absorbing shorter-wavelength radiation.

Mercury Vapor Lamp Principle

Electrons excite mercury atoms, which then emit photons mainly in the ultraviolet range

Phosphor Coating in Fluorescent Lamps

Converts UV radiation into a broader visible-light spectrum

Electron-Hole Recombination

When an electron combines with a hole, energy may be released as a photon.

LED

A p-n junction diode that emits light when forward biased.

semiconductor material

LED Photon Wavelength depends on the _____________________ used in the diode

Aluminum gallium arsenide (AlGaAs)

A semiconductor material used to produce red light in LEDs.

Indium gallium nitride (InGaN)

A semiconductor material used to produce blue light in LEDs

Aluminum gallium phosphide (AlGaP)

A semiconductor material used to produce green light in LEDs

RGB White LED Method

White light is approximated by mixing red, green, and blue monochromatic LEDs

Blue/Conversion White LED Method

A blue LED excites phosphor, which re-emits a broader visible spectrum

Luminous Efficacy (LE)

A measure of how many lumens of light are produced per watt of electrical power.