Question

which physical quantity remains invariant when light travels from one medium to another medium​

Answer 1

$\mathfrak{\large{\underline{\underline{Answer:-}}}}$

Frequency is that physical quantity which remains constant when light travels from one medium to another.

Frequency :- The number of oscillations per unit time of a wave is known as the frequency of the wave.

Frequency remains constant it is same for vacuum and another medium also.

When a light travel from one medium to another only it's velocity is changed but there is no effect in the frequency of light .

Every colour of light has their own fixed frequency .

Answer 2

Answer:

It's Frequency......

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Here is your answer:-

The ray of light or the incident ray which is passing through the centre of curvature retraces its path...