Quantum Theory of Light:
Wave theory failed to describe some new effects in 19th century. A German Physicist Max Plank gave theory about the nature of light.
1. Light is emitted from a source in tiny packets of energy or Quanta.
2. These energy packets or bundles of light known as Photon.
3.The light is emitted and absorbed in the form of Photons.
4.The energy possessed by a photon depends upon its frequency