visible light is only one small part of all the electromagnetic radiation in space. energy is also transmitted in the form of gamma rays,x-rays,ultraviolet radiation,infrared radiation,and radio waves.
because we make such different uses of them,these forms of radiation seem very different from one another. doctors use gamma rays in cancer treatment and x rays for medical diagnosis. ultraviolet rays give you a suntan,and infrared rays warm you up. radio waves are used for communication.
however, all of these forms of radiation are really the same basic kind of energy as visible light. they have different properties because they have different wavelengths. the whole family of electromagnetic waves, arranged according to wavelength, is called the electromagnetic spectrum, which is illustrated in figure 2.4