Submodule 3: Color and the Spectrum
Steve Beeson, Arizona State University
Light is only a small part of the electromagnetic spectrum, the broad range of energies which are produced when electrical charges are accelerated. A small piece of this energy is called a photon, a "light particle" which carries the energy. We can also think of this energy being carried by a wave, with a specific wavelength or frequency. Either way of thinking of light, as a particle of energy (a photon), or a wave carrying energy, is correct and useful.
Most of the electromagnetic spectrum is not accessible to us, unless we're aided by special detectors tuned to the desired energies, much like our eyes are "tuned" to the energy of visible light. Let's "look" at some of the other portions of the spectrum and "see" how they play a part in our lives. Click on the area of the spectrum below that you would like to visit.
Please note that the boundaries of the regions in the electromagnetic spectrum are in no way as sharp as the diagram suggests. For instance, the distinction between ultraviolet light and X-rays is not clearly defined: one person may consider a highly energetic photon an X-ray while another might consider the same photon an ultraviolet photon.
To learn more about photons and the electromagnetic spectrum go to the Color and Light readings.
Light & Optics