Total internal reflection occurs when light travelling through a denser medium strikes a boundary with a less dense medium at an angle exceeding a specific critical angle. As a result, all the light is reflected back into the denser medium, and no light transmits into the second medium.
- Total Internal reflection only takes place when the first medium (where the light originates) is denser than the second medium.
- The critical angle is the angle of incidence above which total internal reflection occurs.
- The critical angle is measured with respect to the normal.
- The normal is an imaginary line drawn in a ray diagram perpendicular to, so at a right angle to (900), to the boundary between two media.
Related diagrams
Each diagram below can be viewed on its own page with a full explanation.
