Maxwell showed that the color of light is determined by the rate or the frequency at which the electromagnetic waves oscillate. The faster it does so, the bluer the light. Red light, the lowest-frequency visible light, is an electromagnetic wave oscillating 450 trillion times a second. Green light oscillates at a higher frequency, at around 550 trillion times a second, and blue light at around 650 trillion times a second. Not only did Maxwell’s theory describe visible colors, but it also predicted the existence of invisible electromagnetic waves.
