CBSE Class 10 Science 2019 · Paper 31/4/3 · Question 3(b)

Light - Reflection and Refraction 2 marks Easy

Define refractive index of a transparent medium. The speed of light in a medium of absolute refractive index

1.5

2 \times 1 0^{8} ms^{- 1}

. What is the speed of light in vacuum ?

Answer

Refractive index is the ratio of the speed of light in vacuum to that in the medium; $c = 3 \times 1 0^{8}$ m/s.

Refractive index: The absolute refractive index of a transparent medium is the ratio of the speed of light in vacuum (or air) to the speed of light in the medium,

n_{m} = \frac{c}{v}

. Speed of light in vacuum:

c = n_{m} \times v = 1.5 \times 2 \times 1 0^{8} = 3 \times 1 0^{8}

m s

^{- 1}

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CBSE Class 10 Science 2019 · Paper 31/4/3 · Question 3(b)

Answer

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