Question
Explain the experiment which represents the total internal reflection.
✓
Answer
→Take a glass beaker with clear water in it. Add a few drops of milk or any other suspension to water and stir the water a few times, 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.
→As shown in fig (a) shine the beam from below the beaker such that it strikes at the upper water surface at the other end. Partial reflection and partial refraction of an incident ray can be observed in water.
→As shown in figure (b) 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 and the incident ray undergoes total internal reflection in water itself.
→Pour this water in a long test tube and shine the laser light from top as shown in fig (c). Adjust the direction of the laser beam such that it is totally internally reflected every time it strikes the walls of the tube.
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