BSL Physics Glossary - total internal reflection - definition
Definition: You need a glass block and a ray of light to see this happen. Shine the ray of light up through the glass block so it comes out into the air. As you change the angle of the ray of light so that the angle of incidence is larger, at a certain point the light will reflect at the surface of the glass and bounce back through the glass block. This is called Total internal Reflection.