# Physics

posted by
**Andrea**
.

The incident ray comes at 30 degrees to normal at the air/glass boundary and is refracted at 18 degrees to normal. a) find index of refraction of glass b)find speed of light in glass c) under what conditions and for what angles will you have total internal reflection in this system (hint consider all paths for incident ray)

a)I'm not completely sure about this question but would I do this:

sin theda 1/sin theda 2 = n2 (where n2 is the index of refraction of the glass)

b)v=c/n =3x10^8m/s/(answer from part a)

c)theda critcal = arcsin(n2/n1) and again you would what ever number n would be from part a) and n2=a because that is the index of refraction of air

Is this setup correct? I am sure that b) and c) are but part a) is the part that is confusing.