Explain experiment which represents the total internal reflection.

Explanation

Take a glass beaker with clear water in it. Stir the water a few times with a piece of soap, so that it becomes a little turbid.
Take a laser pointer and shine its beam through the turbid water. You will find that the path of the beam inside the water shines brightly.

Shine the beam from below the beaker such that it strikes at the upper water surface at the other end it undergoes partial reflection which is seen as a spot on the table below and partial refraction which comes out in the air and is seen as a spot on the roof figure (a).
Now direct the laser beam from one side of the beaker such that it strikes the upper surface of water more obliquely figure (b). Adjust the direction of laser beam until you find the angle for which the refraction above the water surface is totally absent and the beam is totally reflected back to water. This is total internal reflection at its simplest.
Pour this water in a long test tube and shine the laser light from top as shown in figure (C). Adjust the direction of the laser beam such that it is totally internally reflected every time it strikes the walls of the tube. This is similar to what happens in optical fibres.
Note: Take care not to look into the laser beam directly and not to point it at anybody.s face.