Nature and sources of light : Light is a form of energy which on entering our eyes gives the sensation of sight, and enables us to see various objects. Various theories have been purposed for true nature of light. Some theories are discussed below” 1. Newton’s Corpuscular theory (1678) Newton assumed that light is emitted from luminous objects in the form of tiny particles known as corpuscles and travel with the speed of light. He also assumed that these particles travels in straight line and when entered in our retina cause the sensation of vision and different colors are due to the different size of corpuscles. The phenomenon of refraction was explained by assuming that the corpuscles are attracted by the particles of denser medium and are accelerated and hence velocity of light is more in denser medium and this results change in direction. This result is contrary to the fact that velocity of light is less in denser medium. Also other phenomena like interference, diffraction and
