Spectra

A range of different measurements. In terms of physics, spectra usually refers to the different wavelengths, or colors (if in the visible range) of light that can be emitted from a certain element, when excited. For example, sodium emits several shades of yellow and orange when its electrons are excited. This is the same phenomenon that takes place in neon and flourescent lights. These elements are made to emit light by running an electric current through a chamber of their gas form.