In Newton’s 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 velocity but the component along the surface remains unchanged. Considering a ray of light going from a rarer medium (air) to a denser medium (water). Let c = speed of light in vacuum (or air), v = speed of light in water, i = angle of incidence, and r = angle of refraction Then according to Newton’s corpuscular theory, Component of velocity c along surface of separation = Component of velocity v along the surface of separation ∴ c sin i = v sin r or $\frac{v}{c}$ = $\frac{\sin i}{\sin r}$ = $\,\mu_{w}^{a}$ As $\,\mu_{w}^{a}$ > 1 , therefore, v > c. So, according to Newton’s corpuscular theory the speed of light in medium is larger than speed of light in air. v > c but in fact the experimental observation shows that speed of light is smaller in denser medium as compared to rare medium v < c.