How is the refractive index of a medium related to the speed of light ? Obtain an expression for refractive index of a medium with respect to another in terms of speed of light in these two media ?

How is the refractive index of a medium related to the speed of light

1.	How is the refractive index of a medium related to the speed of light ? Obtain an expression for refractive index of a medium with respect to another in terms of speed of light in these two media ?
Answer» Solution :If medium 1 is VACUUM or AIR medium 2 is GLASS, then the refractive INDEX of medium 2 considered with respect to vacuum or air is represented as `mu_(21)=mu_(ga)=mu_("glass")` Then `mu_(21)` is the ABSOLUTE refractive index of medium 2. Hence `mu_("glass")=("speed of light in air / vacuum")/("speed of light in medium 2 (say glass)")=(c )/(v_(2))` If we consider a light ray travelling from medium 2 to medium 1, refractive index of medium 1 with respect to medium 2 `= mu_(12)`. `mu_(12)=("speed of light in medium 2")/("speed of light in medium 1")=(v_(2))/(v_(1))`