The index of refraction of diamond is 2.42. What would be the speed of a light wave passing through a this medium?

8.1 x 10 ^-9 m/s
1.2 x 10^8 m/s
7.3 x 10^8 m/s
9 x 10^-9 m/s

1 answer

3*10^8/2.42

http://hyperphysics.phy-astr.gsu.edu/hbase/geoopt/refr.html

Hey, do you not have a text?