Question

what is the meaning of unity in light chapter?​

Answer 1

Answer:

A new unit of length is chosen such that the speed of light in a vacuum is unity. ... Distance between the Sun and the Earth = Speed of light × Time taken by light to cover the distance.

Explanation:

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Answer 2

(b)."Since the speed of light is maximum in vacuum, the refractive index be "less than unity".

Explanation:

• A new unit of length is chosen such that the speed of light in vacuum in unity. Distance between the sun and earth = Speed of light × time taken by light to cover the distance.
• The absolute refractive index of a medium can not be less than one because the speed of light in any medium is always less than that in a vacuum.
• So, ratio of  $\frac{c}{v}$ is always more than 1. hence, absolute refractive index of any material can never be less than 0.