State the postulates & drawbacks of Newton’s corpuscular theory.

 Postulates of Newton’s corpuscular theory:

Every source of light emits large number of tiny particles known as ‘corpuscles’ in a medium surrounding the source. These corpuscles are perfectly elastic, rigid and weightless. The corpuscles travel in a straight line with very high speeds which are different in different media.One gets a sensation of light when the corpuscles fall on the retina. Different colours of light are due to different sizes of corpuscles. 

Drawbacks of Newton’s corpuscular theory:

It could not explain partial reflection and refraction at the surface of a transparent medium. It was unable to explain phenomenon such as interference, diffraction, polarisation etc. This theory predicted that speed of light in a denser medium is more than the speed of light in a rarer medium which was experimentally proved wrong by Foucault.

Hence Newton’s corpuscular theory was rejected. When particles are emitted from the source of light, the mass of the source of light must decrease but several experiments showed that there is no change in the mass of the source of light.

State the merits and demerits  of Huygens’ wave theory of light.

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