The speed of light is different in different media. When light enters a denser medium, then its speed reduces, and the light travels faster when it enters a rarer medium with a low refractive index. Hence the refraction index of light is inversely proportional to the speed of light entered. Velocity of electrons is inversely proportional to radius of the orbit and in an atom; the velocity of electrons in the higher orbits keeps on decreasing. The velocity of electron in an orbit is inversely proportional to the radius of the orbit. As the refractive index of a material increases, the greater the extent to which a light beam is deflected upon entering or leaving the material. The relationship between the angle of incidence and angle of refraction is explained by Snell's law, which states that the ratio of the sine of the angle of refraction and the sine of the angle of incidence is always constant and equivalent to the ratio of phase velocities of the two mediums it is passing through. The speed of light is faster in water. The refractive index of water is 1.3 and the refractive index of glass is 1.5. From the equation n = c/v, we know that the refractive index of a medium is inversely proportional to the velocity of light in that medium. Hence, light travels faster in water. Refractive index of a medium as the ratio of the velocity of light in air and the velocity of light in that medium. Refractive index, μ = c v, c is the velocity of light in air and v is the velocity of light in the medium. Hence, the refractive index of a medium is inversely proportional to the speed of light in that medium.