Refraction/ total internal reflection

Ok, so when light goes from a fast medium to a slow one it bends towards the normal, and when it goes from a slow medium to a fast one it bends away from the normal, I hope.

Now, in this question it showed a boundary between 2 materials, and said that material 1 had a lower refractive index than material 2. Then it told me to draw the line going into boundary 2 and into the air.

So I assumed lower refractive index = slower material, so it's slow going into fast. So I drew the line going away from the normal.

But then the mark scheme says it goes TOWARDS the normal.

So does a low refractive index mean that it's fast?

Yes low refractive indes means the light travels more quickly through it. If you think of a vacuum having a refractive index of 1, it makes more sense

Oh right, that's good then, so light goes really slowly through diamond?

Yep. Refractive index of over 2 I think.

Think I finally get refraction and total internal reflection, then.

Let's see how I do in this paper though.

Thanks for the help.

Ah, remembered how you work it out:

absolute refractive index = speed of light in material / speed of light in vacuum

Refractive Index can be calculated by two ways
1- n= speed of light in vacuum/ speed in medium.

2- n= sin of angle of incidence/ sin of angle of refraction.

both are equal