00:01
So in this problem, we're told that the speed of light is 89 % of its value in water.
00:10
Oh, the speed of light in a certain substance is 89 % of its value in water.
00:16
And we want to get the index of a fraction of the substance.
00:21
So we can say v in substance over v in water is equal.
00:36
To, i just want to make sure i get this right.
00:43
I would say that's equal to 0 .89.
00:50
And yeah, we're looking to get n.
00:52
So we can use n is equal to, in general, c over v.
01:00
So v of the substance, oh, wait, no, no, no.
01:09
So this is true...