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?
According to Newton’s Corpuscular theory, velocity of light in the denser medium (water) is greater than the velocity of light in the rarer medium (vacuum). This was
At the angle of incidence (i) of the light of velocity v, the angle of refraction is r.
Due to the change in the medium, the change in the velocity of light in water is v
Using Snells law,
c sin i = v sin r ——(1)
The relation between the velocities and the refractive index is
v/c = μ ———(2)
v/c = sin i/sin r = μ ——-(3)
But μ> 1 so v > c is not possible
Huygens wave theory is consistent with the experiment.