Given that;
Refractive index (μ) = 1.33 = \(\frac43\)
Speed of light in air(c) = 3 x 108;
Speed of light in water =?
We know that
µ = \(\frac{c}{v}\)
\(\frac43\) = \(\frac{3\,\times\,10^8}{v}\)
⇒ v = \(\frac{3\,\times\,3\,\times\,10^8}{4}\,=\,\frac{9\,\times\,10^8}{4}\)
⇒ v= 2.25 × 108m/s.
Hence speed of light in water is 2.25 × 108m/s.