Cod liver oil - a potentially toxic source of Vitamin A: Hypervitaminosis A can result from ingestion of too much vitamin A from diet, supplements, or prescription medications.
This visible light region consists of a spectrum of wavelengths that range from approximately 700 nanometers (abbreviated nm) to approximately 400 nm. Expressed in more familiar units, the range of wavelengths extends from 7 x 10 -7 meter to 4 x 10 -7 meter.
Note that this is the energy per quantum (photon if in the visible range) but not the total energy; the latter is a function of the intensity in a beam. We can detect the range of light spectrum from about 400 nanometers (violet) to about 700 nanometers (red). We perceive this range of light wavelengths as a smoothly varying rainbow of colors, otherwise known as the visual spectrum.