Wavelength is the distance between two points of the same phase in consecutive cycles on a periodic wave. Wavelength can be expressed in many units of distance, the most logical being the meter. However, because so many kinds of electromagnetic radiation are of very short wavelength some smaller units are necessary. Some of the most common units of measure for wavelength are the centimeter, the nanometer (1x10-9 m), and the angstrom (1x10-10 m). The angstrom is named for the Swedish physicist Anders Angstngström who used this unit as a basic unit of measurement for his studies of the solar spectrum in the mid-1800s. Visible light (for humans) has wavelengths ranging from roughly 400 nm to about 750 nm.

When light passes from one transparent material to another, with differing refractive indices, it is refracted or bent, the extent of which is determined by the wavelength...