Ravi is a student of mechanical engineering studying in one of the engineering colleges. The other day he saw an old man who suddenly collapsed as he walked out of the house in his neighbourhood. Ravi the emergency ward of the hospital. On getting the medical aid, the old man soon goy recovered. He did not forget to thank Ravi for the timely help he rendered. He was wondering that in his times to get the telephone connection. One had to wait for years whereas these days it takes no time to get the connection. Ravi told him it was all because of the technological progress/deveolpement due to which the simple phenomenon in physics could be easily used.
Answer the following questions based on the above :
(a) To which phenomenon in physics was Ravi referring to, which made the land line links so easily accessible?
(b) What are the essential conditions required to observe this phenomenon ?
(c) Write two values displayed by Ravi and the old man in this episode.

Explanation

(a) (i) Total internal reflection.
(b)(i) Light should go from denser mdeium to rarer medium.
(ii) Angle of incidence should be greaterf than critical angle.
(c) Values displayed by Ravi (i) Helpful (helping attitude),(ii) Knows how to use modern technology. By old man : (i) Thankful , (ii) Surprised to see changes in technology.