Wavelength, l, - visible Region- approx. 350 nm to 700 nm (nm = nanometres).
Energy increases towards shorter wavelength, towards ultraviolet.
E = hn = hc/l
h = Planck�s constant = 6.626196 x 10-27 erg sec
c = speed of light = 2.9979 x 1010 m s-1
We commonly use 1/l as a unit of energy, so-called inverse cm, or cm-1 or wqvenumbers.
Visible region is from about 14,300 cm-1 (red) to 28,600 cm-1 (blue).
or in electron volts: (eV)
red 1.77, to blue 3.55 eV