Physics
What is refractive index ?

It is defined as the ratio of speed of light in the medium to the speed of light in vacuum.
None of above
It is defined as the ratio of speed of light in vacuum to the speed of light in the medium.
It is defined as the product of speed of light in medium and in vacuum.

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Physics
Which one of the following statements with regard to Jet stream, an upper level tropospheric wave, is not correct?

It follows the wave path near the tropopause at elevations of 8 km to 15 km.
In summer, the polar front jet achieves its maximum force.
Jet streams are typically continuous over long distances.
It is narrow band of high-velocity wind.

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