**Critical angle**

**03/07/17**

*“Can we use refraction to make reflection?”*

Refraction is a common physical phenomenon, and we know that if light from a denser medium passes into a lighter medium then it will bend further away from the normal angle. However, is it possible that this angle can bend so much that it will actually **go back into the incident medium? **Well, let’s use our scientific mindset to investigate this question. We know that light passing between two mediums behaves as dictated by snell’s law, or n1sin(1)=n2*sin(2). If we were to arrange this equation to find for 2, we would arrive at 2=sin(n1*sin(1)/n2)-1. Now if we analyze this equation, we can realize that if were to have the ray of light incident at an angle 1such that the output would be 90 degrees, the light **would not pass to the other side! **Physicists have termed this angle the **critical angle **and is used heavily in fiber optics, where light is trapped in and passes through a long tube of wire.