In the wave picture, the energy increases as the wavelength decreases. The wavelength of light determines its color.
Red light has a longer wavelength than blue light.
In addition to the electromagnetic radiation that we see as visible light, many electromagnetic waves are invisible to the eye, such as infrared, ultraviolet , radio, x-rays, and gamma rays. The entire assemblage of electromagnetic waves is called the electromagnetic spectrum . Energy can be absorbed by or released from an atom when an electron moves to a higher or lower orbit, respectively. If an electron drops from an upper to a lower orbit, the energy appears as light. The generation of light is called emission .