Snell's Law: From n sin theta to n1sintheta1 = n2sintheta2

[mauifq]

Hi, I'm new to the forum as I'm struggling to find answers with an internet search.

I've seen Snell's Law stated as n sin theta = constant.

How does this arise from its more familiar form of n1sintheta1 = n2sintheta2? I can't work it out.

Thanks for reading!

 

[ShayanJ]

Well, that's in fact something very straight forward and has no intermediate mathematical steps. Its just that when something is not changing while time goes on, then its constant. So when light is moving between different media and , although different media have different refraction indices and the light experiences different angles of refraction, it will always have the same $n \sin\theta$. So this quantity doesn't change, so its a constant!