CBSE Class 10 Science 2019 Outside Delhi Set 1

Question : 5 of 27

Marks: +1, -0

The absolute refractive index of Ruby is

{1 . 7}

. Find the speed of light in Ruby. The speed of light in vacuum is

3 × 10^8 {\m} \/ {\ s}

Solution:

We know that,
Refractive index of ruby

(µ)

=\;{\;\text " Speed of light in air (or vacuum) "\;}/{\;\text " Speed of light in ruby "\;}

So,

1 ⋅ 70=\;{3 × 10^8}/{\;\text " Speed of light in ruby "\;}

\;\text " or Speed of light in ruby "\;=\;\;{3 × 10^8}/{1.7} {\ms}^{-1}

\;=1.76 × 10^8 {\ms}^{-1}

Thus, speed of light in ruby is

1.76 × 10^8 {\ms}^{-1}

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