Question

(i) Define 'refractive index.
(ii) The refractive index of glass is 1.50 and the speed of light in air is 3 x
$ten to the power eight$

ms-1. Calculate the speed of light in glass.​

Answer 1

$\red{\mid{\underline{\overline{\textbf{Answer}}}\mid}}$

i) Refractive index of a medium is defined as the ratio of speed of light in air to speed of light in given medium. It has no units and is represented by :-

$\bigstar \: \mu = \huge \frac{c}{v}$

In this expression :-

• $\mu$ = Refractive index
• c = speed of light in air
• v = speed of light in given medium.

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ii) We have been given that :-

• c =$3 \times {10}^{8} m \div s$
• $\mu$ = 1.50
• v = ?

Now we know that :-

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

After inputting the values we get :-

$\mapsto \: 1.50 = \frac{3 \times {10}^{8} }{v}$

$\mapsto \: v = \frac{3 \times {10}^{8} }{1.50}$

$\mapsto \: v = \huge \cancel \frac{3 \times {10}^{8} }{1.50}$

$\mapsto \: v = 2 \times {10}^{8} \frac{m}{s}$

Therefore the speed of light in glass is $2 \times {10}^{8} m/s$

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BY SCIVIBHANSHU

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