Look at the black, two way arrow in the image showing the distance between two nearest wave troughs. The distance between 3 angstroms and 2 angstroms is 1 angstrom. That means the length of this wave is 1 angstrom.

Angstroms are units of distance that scientists often use to measure the wavelengths of light, rather than feet or inches. Why? You'll find out more about angstroms later on. What type of light has a wavelength of 1 angstrom? If you don't know now, don't worry! You'll know the answer by the end of this light tour!

Why Measure the Waves? The various types of light that make up the electromagnetic spectrum differ in the length of their waves. This is important because each wavelength carries a different amount of energy. Each wavelength has a certain characteristic energy, and shorter wavelengths carry more energy than longer wavelengths. The reason for this is similar to why it takes more energy to move something back and forth quickly, than it does to more it slowly. For example, a ripple tank needs more energy from its motor to many short waves than to make longer ones.