colour

LED Wavelength (Colour)

Wavelength(λ) is measured in nanometers(nm), Every Color has its own frequency or can be made up of a mixture of LEDs such as white that is all three primary colours of light Red, Green and Blue.

note when using paints artists use three primary colours of Red, Yellow and Blue plus Black and White paint.

NOTE: LEDs include the invisible to humans infrared frequencies (1 and 2 in chart below), many people may well be red colour blind to 700nm(3 in chart).

Relative Intensity vs Wavelength (P)

From the above chart LED (D, Ultra Blue) can reach into the invisible to humans Ultraviolet (UV) frequencies above 2.75 THz(380nm wavelength) which is a band gap of –3.26 eV(electron Volts)

Knowing the 'band gap' is useful for designing the drive circuit as the LED will need this forward voltage to work.

LEDs can be used as voltage references for a transistor current source circuit, also used for setting up thresholds. Each LED's forward voltage drop needs to be tested and varies with current ( refer to the manufacturer's specifications sheets, Check the Forward Current vs. Forward Voltage Chart).

LED colours 940 to 585nm using Gallium

LED colours higher frequencies (shorter wavelengths)

λ (Lamda) is the greek symbol used in science for wavelength

λ is equal to the inverse of frequency with respect to its velocity the speed of light (c)