Please explain with the help of a ray diagram:-
  • An optical fibre is used to transmit a light signal over a long distance without the loss of energy. However some energy gets lost due to absorption of light in its material.
  • A piece of diamond sparkles when viewed from certain directions.
  • A crack in a glass vessel often shines like a mirror.
  • An empty test tube placed in water in a beaker with mouth outside the water surface, shines like a mirror when seen at certain angles.
  • On a hot sunny day. a driver may see a pool of water or a wet road in front of him at some distance which is similar to the phenomenon of mirage, often observed in a desert.

Asked by Vandana | 20th Jun, 2017, 12:03: PM

Expert Answer:

Diamonds sparkle more than other materials due to total internal reflection coupled with a large index of refraction.
The critical angle for a diamond-to-air surface is only 24 °. When a ray of light enters a diamond it undergoes a series of total internal reflections due to the very small critical angle. This traps the ray of light due to which sparkles 
As a result, the ray of light gets trapped for some time within the diamond. So, it is due to this trapped energy that makes the diamond sparkle.
NOTE: Kindly ask the other ray diagram as a separate query each.

Answered by Yashvanti Jain | 21st Jun, 2017, 07:08: PM