Question

Refractive index of glass is 1.5. If the speed of light in vacuum is 3 X 10^8 m/s, find velocity of light in medium.[10^8 = ten to the power 8]

Answer 1

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Wr have been given that :-

• Refractive Index of glass = 1.5
• Speed of light in vaccum = $3 \times {10}^{8} \frac{m}{s}$
• Speed of light in glass = ?

Now, we know that refractive index of a medium is the ratio of speed light in Air or vaccum to the speed of light in the given medium. This is represented by :-

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

Now after inputting the know values in this equation we get :-

$1.5 = \frac{3 \times {10}^{8} }{v}$

$v = \frac{3 \times {10}^{8} }{1.5}$

$v = \frac{30 \times {10}^{8} }{15}$

$v = \cancel \frac{30}{15} \times {10}^{8}$

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

Therefore we get speed of light in glass to be 2 × 10^8 m/s.

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BY SCIVIBHANSHU

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