The fundamental quality characterizing a photon, equivalent to its energy. Differing visible wavelengths are perceived as different colors.dxoglossary
The distance from peak to peak in a light wave that determines the color of the light.
A unit of measurement, from on crest to the next, in the spectrum, stated as nanometer (one billionth of a meter).
The distance between waves in the electromagnetic field, specified as angstroms or Nanometers.