Refractive indeX \(=\frac{\text { speed of light in vacuum }}{\text { speed of light in medium }}\)
Since the refractive index of diamond is more, hence the speed of light is lesser in diamond.
Let speed of light in water vev \(_{w}\) and in diamond bev \(_{d}\).
Refractive index of diamond w.r.t water is say \(\mathbf{n}=\frac{\text { speed of light in water }}{\text { speed of light in diamond }}\) \(n=\frac{V_{w}}{V_{d}}\)
Dividing both numerator and denominator by speed of light [c] we get
\(\mathrm{n}=\left(\frac{V_{w}}{c}\right) \div\left(\frac{V_{d}}{c}\right)=\) Inverse Ratio of refractive index of water and diamond.
\(\mathrm{n}=\frac{2.42}{1.33}=1.82\) (арргох.)
