Visible light is just a small part of a continuum of electromagnetic radiation that extends from radio waves to gamma rays. Phenomena as diverse as radio waves used to transmit information, microwaves used to cook food, and x rays used for medical purposes are all part of the electromagnetic spectrum. Although each type of radiation has distinct properties, they can all be described in the same simple terms.

The characteristic of electromagnetic radiation that causes its properties to vary is its wavelength. The wave-like properties of electromagnetic radiation are similar to the waves created when an object is dropped into water. The wavelength of the wave is the distance between two successive peaks. The wavelength of radiation is sometimes given in units with which we are familiar, such as inches or centimeters, but for very small wavelengths, they are often given in angstroms (Å). (10,000,000,000 Å equals...