The refractive index of water is 1.33 and the speed of light in air is 3×108 ms−1. Calculate the speed of light in water.

Refractive index (n) = 1.33

Speed of light in air = 3x 10⁸ ms^-1

Speed of light in water = ?

The refractive index is given by n= c / v

Substituting the given values in the above equation, we will get

v = c / n

= 3×10⁸ m/s / 1.33

∴ v = 2.25×10⁸ m/s

So, the speed of light in glass would be 2.25×10⁸ m/s.