Explain how Corpuscular theory predicts the speed of light in a medium, say, water, to be greater than the speed of light in vacuum. Is the prediction confirmed by experimental determination of the speed of light in water ? If not, which alternative picture of light is consistent with experiment?

Explanation

In corpuscular (particle) picture of refraction, particles of light incident from a rarer to a denser medium experience a force of attraction normal to the surface. This results in an increase in the normal component of the velocity but the component along the surface is unchanged. This means
`c sin i=v sin r or (v)/(c)=(sini)/(sinr)=n`. since `n gt 1, v gt c`.
The prediction is opposite to the experimental results `(v lt c )`. The wave picture of light is consistent with the experiment.