Explanation:
Light is not the only type of electromagnetic radiation
—it is, in fact, only a small segment of the total
electromagnetic spectrum—but it is the one form the
eye can perceive. Wavelengths of light range from
about 400 nm at the violet end of the spectrum to 700
nm at the red end ( see table). (The limits of the
visible spectrum are not sharply defined but vary
among individuals; there is some extended visibility
for high-intensity light.) At shorter wavelengths the
electromagnetic spectrum extends to the ultraviolet
radiation region and continues through X-rays ,
gamma rays, and cosmic rays. Just beyond the red
end of the spectrum are the longer wave infrared
radiation rays (which can be felt as heat),
microwaves , and radio waves. Radiation of a single
frequency is called monochromatic. When this
frequency falls in the range of the visible spectrum,
the colour perception produced is that of a saturated
hue.
