electromagnetic
Visible light is one type of electromagnetic radiation , which is a form of energy that exhibits wavelike behavior as it moves through space. Other types of electromagnetic radiation include gamma rays, x-rays, ultraviolet light, infrared light, microwaves, and radio waves. The figure below shows the electromagnetic spectrum , which is all forms of electromagnetic radiation. Notice that visible light makes up only a very, very small portion of the entire electromagnetic spectrum. All electromagnetic radiation moves through a vacuum at a constant speed of 2.998 10 8 m/s. While the presence of air molecules slows the speed of light by a very small amount, we will use the value of 3.00 10 8 m/s as the speed of light in air.