Light is an electromagnetic radiation that can be detected by humans. Electromagnetic radiation happens in an extremely large range of wavelengths from gamma rays to radio waves. Within that spectrum the wavelengths visible to humans are few. Light is very difficult to define, in the sense that scientist have been arguing weather light is a particle or a wave. Many experiments have been done to proof weather light is a particle or a wave. The truth is that light sometimes acts as a wave and sometimes as a particle. In the famous Young's double-slit experiment, a coherent beam of light is directed through two slits and then onto a photographic plate. When each photon hits the plate, it makes a single, point-like mark, indicating that the photon
