Section D: Give a long answer to the question given below.
(i) What is an echo?
(ii) State two conditions necessary for hearing an echo.
(iii) What are the medical applications of echo?
(iv) How can you calculate the speed of sound using echo?
(ii) State two conditions necessary for hearing an echo.
(iii) What are the medical applications of echo?
(iv) How can you calculate the speed of sound using echo?
(i) An echo is the sound reproduced due to the of the original sound from various such as walls, ceilings, surfaces of mountains, etc.
(ii) Conditions necessary for hearing echo:
The persistence of hearing for human ears is . Thus, the minimum time gap between the original sound and an echo must be .
(ii) Conditions necessary for hearing echo:
The persistence of hearing for human ears is . Thus, the minimum time gap between the original sound and an echo must be .
The minimum distance required to hear an echo is part of the magnitude of the velocity of sound in air. The minimum distance required to hear an echo is .
(iii) The principle of echo is used in , which is used to create real-time visual images of the developing embryo or fetus in the mother’s uterus. This is a , as it any harmful radiations.
(iv) The sound pulse emitted by the source travels a total distance of . The time taken for this has been observed to be . Hence, the speed of sound wave is given by .
(iv) The sound pulse emitted by the source travels a total distance of . The time taken for this has been observed to be . Hence, the speed of sound wave is given by .