the index of refraction of fused quartz is 1.2 for light of wave length 500nm find the speed of light of these wavwlengths in fused quartz.

refractive index n = 1.2

wavelenght  = 500nm

     speed of light

            n = c/v

             v = c/n

              v = 3x10^8/1.2

             v = 2.5x10^8m/s