Light is energy that travels in electromagnetic waves, meaning it can travel through a medium (matter) or through a vacuum (empty space). The speed of light is 300,000,000 meters/second.

An electromagnetic wave consists of changing electric and magnetic fields. Radiation is the transfer of light as electromagnetic waves. Photons are the particles of light that travel in waves. They are not considered matter and are better described as little packets of energy.

The Electromagnetic Spectrum and Visible Light The narrow band of light that we can see is called visible light, or white light. Visible light waves have wavelengths between 400 and 700 nanometers (one-billionth of a meter)

White light consists of an array of colors having different wavelengths. Refraction is the bending of a wave as it passes at an angle from one medium to another. When it passes through a glass prism, white light can disperse into its component colors according to wavelength (the light spectrum). Colors with shorter wavelengths will deviate more from their original path. Light can also be absorbed into matter, or reflected.