What is the speed of light in a medium of refractive index $\frac {6}{5}$ if its speed in air is 3,00,000 km/s?

Given:

Speed of light in air = 3,00,000 km/s

Refractive index of the medium = $\frac {6}{5}$

To find: Speed of light in the given medium.

Solution:

From the formula of refractive index, we know that:

$Refractive\ index\ of\ a\ medium=\frac{Speed\ of\ light\ in\ air}{Speed\ of\ light\ in\ medium}$

Substituting the given values in the formula, we get-

$\frac {6}{5}=\frac {3,00,000}{Speed\ of\ light\ in\ medium}$

$Speed\ of\ light\ in\ medium=\frac {5\times 300000}{6}$

$Speed\ of\ light\ in\ medium=5\times 50000$

$Speed\ of\ light\ in\ medium=250000km/s$

Thus, the speed of light in the given medium is 2,50,000 km/s.

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Updated on: 10-Oct-2022

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