ABSTRACT
The visible light used by photographers to produce images is just one part of a range of 'electromagnetic' radiations. The infrared (IR) section of the electromagnetic spectrum is generally regarded as being composed of three parts namely: near, middle and far infrared. Electromagnetic radiation is a radiant energy which exhibits wave-like motion as it travels through space. As light travels through space it exhibits wave-like motion. Waves have three properties namely: wavelength, frequency and speed. All electromagnetic radiation travels at the same speed in a vacuum. The use of wavelength at the extreme ends of the electromagnetic spectrum becomes less helpful; at very high energies the wavelength is so short and its frequency so high it is usual to quantify a light wave by the amount of energy it transfers to a surface, that is, the energy of its photons. Different colours correspond to different wavelengths and frequencies of visible electromagnetic radiation.
