Question

what is the speed of light in a medium of R.I. 6/5 if its speed in air is 3,00,000 km/s?

Answer 1

speed of light=speed of light in air/refractive index
speed of light=300000/6/5
=300000"5/6=250000km/s


hope it helps

Answer 2

Speed of Light  =  Speed of light in air / Refractive index
Speed of Light= 300000 /6 /5
                        =  300000"5/6=250000km/s