What is refraction of light? How is refractive index of material related to velocity of light?

Explanation

Refraction of light:
Light changes its direction when passing from one transparent medium to another transparent medium. This is called the refraction of light. Relationship between refractive index and velocity of light:
i. The extent of change in the direction of light ray is different for different media and depends upon the refractive index of medium.
ii. The value of refractive index is different for different media and it depends on the velocity of the light in the medium.
iii. The refractive index `(""_(2)n_(1))` of second medium with respect to the first is given by the ratio of the magnitude of velocity of light in first medium `(v_(1))` to that in second medium `(v_(2))`, i.e.,
`""_(2)n_(1)=("velocity of lgiht in first medium "(v_(1)))/("velocity of light in second medium "(v_(2)))`
iv. Refractive index of medium 1 with respect to medium 2 is `""_(1)n_(2)=(v_(2))/(v_(1))`
Thus, the refraction of light depends upon refractive index of the material which in tum depends on velocity of light in medium.