Light enters from air to water having a refractive index 4/3. Find the speed of light in water if the speed of light in vacuum is 3x108m/s.


Given: Refractive index of water is 4/3.

To find:  Speed of light in water

Solution:

We know,

Refractive index of water $=\frac{\text {Speed of light in vacuum}}{\text {Speed of light in water}}$

So, $ \frac{4}{3}=\frac{3 \times 10^{8}}{\text { speed of light in water}}$

Speed of light in water $=\frac{3 \times 10^{8}}{ \frac{4}{3}}$

Speed of light in water $=\frac{3 \times 3\times 10^{8}}{4}$

Speed of light in water $=\frac{9 \times 10^{8}}{4}$

Speed of light in water $=2.25 \times 10^{8} \mathrm{m} / \mathrm{s}$

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Updated on: 10-Oct-2022

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