The absolute refractive index of Ruby is 1.7. Find the speed of light in Ruby. The speed of light in a vacuum is 3 × 10⁸ m/s.

Given:

Refractive index of ruby, $\mu_R \ =  \ 1.7$

Speed of light in vacuum, $c \ = \ 3\times {10}^{8}m{s}^{-1}$

To find: Speed of light in ruby, $v$.

Solution:

We know that,

$\mu =\frac{c}{v}$

where,

$\mu$ = refractive index.

$c$ = velocity of light in a vacuum.

$v$ = velocity of light in a substance.

Substituting the given values we get-

$1.7=\frac{3\times {10}^{8}}{v}$

$\frac{17}{10}=\frac{3\times {10}^{8}}{v}$

$v=\frac{3\times {10}^{8}\times 10}{17}$

$v=\frac{30\times {10}^{8}}{17}$

$v=1.76\times {10}^{8}m/s$

Hence, the speed of light in ruby is 1.76 x 10⁸m/s.

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Updated on: 10-Oct-2022

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