Correct Answer - Option 2 : 2.25 × 10
8 m/s
Concept:
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The absolute refractive index of a medium: The ratio of the speed of light in air or vacuum to the speed of light in the given medium is called the absolute refractive index of the medium.
\(μ = \frac{c}{v}\)
μ is the absolute refractive index, c is the speed of light in air, v is the speed of light in the given medium.
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Relative refractive index: The ratio of the speed of light in a transparent medium 1 to the speed of light in transparent medium 2 is called the refractive index of medium 2 with respect to medium 1.
- In general, the refractive index is a term used for an absolute refractive index.
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Speed of light in air is approximately equal to 3 × 10 8 m /s
Calculation:
Given Speed of light in vacuum c = 3 × 10 8 m /s
speed of light in water v = ?
Refractive index of water μ = 1.33
So,
\(μ = \frac{c}{v}\)
\(\implies 1.33 = \frac{3 \times 10^8}{v}\)
\(\implies v = \frac{3 \times 10^8}{1.33}\)
⇒ v = 2.25 × 108 m/s
So, the correct option is 2.25 × 108 m/s
