Be remember











Again Suppose there have three medium a, b, c, then








Example 1: suppose refractive index of diamond with respect to air is 2.42, that is








Then refractive index of air with respect to diamond is













 
Example 2: consider refractive index of water w.r.t. air is 1.33







Refractive index of air w.r.t. glass is 0.658








Then








This is the refractive index of water w.r.t. glass (0.8751)