Can someone explain total internal reflection in very basic wording?
Total internal reflection is a phenomena where a light (but it could be any wave type) attempts to exit an optically dense medium (example: water) and enter an optically sparse medium (example: air). Notice that I used the word “attempts”. Consider shining a flashlight from within a body of water. If you shine this light directly upward, it has normal incidence. some of the light will escape to air in a straight line, some will reflect internally within the water. If you shine this light slightly misaligned from under water, it will refract at an angle greater than the angle of incidence. Now, the mathematics of Snell’s law create some interesting, but frustrating conditions at an angle of incidence called the critical angle. Plug in the critical angle for angle of incidence, and it will predict that the angle of refraction will be 90 degrees. Can light refract such that it “grazes” the water-air surface and never rises above the water? That is what Snell’s law predicts at the critical
