- 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 and partial refraction.
- Now direct the laser beam from one side of the beaker such that it strikes the upper surface of water more obliquely.
- Adjust the direction of laser beam until you find the angle for which the refraction above the water surface is totally absent.
- The beam is totally reflected back to water. This is called as total internal reflection.
Experiment 2:
- Pour the turbid water in a long test tube.
- Shine the laser light from top.
- Adjust the direction of the laser beam such that it is totally internally reflected every time it strikes the walls of the tube.
- This demonstrates total internal reflection.
