Wavelength

Electromagnetic radiation includes visible light, ultraviolet light, infrared radiation, and radio waves. In classical electromagnetic field theory, electromagnetic radiation propagates as a pair of coupled electrical and magnetic fields. A time varying electrical field creates a time varying magnetic field that in turn creates a time varying electrical field that creates a time varying magnetic field that creates a time varying electrical field, and so on. The distance over which the electrical (or magnetic) field at a given instant varies from its maximum to its minimum and back is the wavelength of the radiation. Interactions between radiation and matter depend on wavelength. In the human visual system, wavelength is intimately connected with color. A wavelength of the order of 440 nm is perceived as blue, 740 nm as red and the human eye is relatively insensitive to wavelengths longer than 800 nm. On fundamental physical grounds, the resolution of optical systems is generally...