Question

Question #56175

Answer 1

1.5.

Explanation:

The refraction index `n` is defined as the ratio between the speed of light in the vacuum, `c`, and its velocity in a given medium, `v`; that is:

`n = c/v`.

Then, using `c = 3.10^8 m/s` and that `v = 2x10^8 m/s` (I am assuming the `10^8` factor here, because I believe you might have forgetten something in your question):

`n = (3.10^8)/(2.10^8) = 1.5.`

However, if the velocity is, indeed, `v = 2 . 10 m/s` you simply have to use the correct value in the equation above. :)

Hope it helped!