If suitable values are chosen for these constants, the formula can be made to represent the dispersion of ordinary transparent media within the visible spectrum very well, but when extended to the infra-red region it often departs considerably from the truth, and it fails altogether in cases of anomalous dispersion.
The only way in which the secondary spectrum can be reduced still further is by the employment of three lenses of three different sorts of glass, by which arrangement the secondary spectrum has been reduced in the case of the Cooke photo visual objective to about I/loth part of the usual amount, if the whole region of the visible spectrum is taken into account.
The rays of the visible spectrum do not supply all the energy which the plant obtains.
A false color image is generated from the EDX maps by assigning the visible spectrum to a suitable band of X-ray energies.
The visible spectrum has a wavelength from red's approximately 700 nm (nanometers = billionths of a meter) to violet's mere 400 nm.
