Question

The speed of light in a transparent medium is 1.7 x 108 m/s. what is the index of refraction of this medium?

Answer 1

The index of refraction of a medium is defined as
$n= \frac{c}{v}$
where
c is the speed of light in vacuum
v is the speed of light in the medium

For the medium in our problem, $v=1.7 \cdot 10^8 m/s$, so if we apply the previous formula we find the index of refraction of the medium:
$n= \frac{c}{v}= \frac{3 \cdot 10^8 m/s}{1.7 \cdot 10^8 m/s} =1.76$