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प्रश्न
On which day, a hot day or a cold day, an echo is heard sooner ? Give reason for your answer.
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उत्तर
An echo is heard sooner on a hot day because the speed of sound in air increases with increase in temperature of the propagating medium. Therefore, the speed of sound in air is faster on a hot day and thus echo is heard sooner.
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संबंधित प्रश्न
A man is standing at a distance of 12 m from a cliff. Will he be able to hear a clear echo of his sound? Give a reason for your answer.
Explain why, the flash of lightning reaches us first and the sound of thunder is heard a little later.
Why are the ceilings of concert halls made curved ? Draw a labelled diagram to illustrate your answer.
Explain by giving a scientific reason.
We cannot hear the echo produced in a classroom.
State two conditions necessary for hearing an echo.
What are the medical applications of echo?
When sound is reflected from a distant object, an echo is produced. Let the distance between the reflecting surface and the source of sound remain the same. Do you hear an echo sound on a hotter day? Justify your answer.
Assertion: The sound which we hear again is called Echo.
Reason: The sensation of sound (Echo) persists in our brain for about 1 s.
Numerical problems:
An echo returned in 3s. What is the distance of the reflecting surface from the source given that the speed of sound is 330 ms-1?
Rohan conducted experiments on echo in different media. He observed that a minimum distance of 'x' meters is required for the echo to be heard in oxygen and 'y' meters in benzene. Compare 'x' and 'y'. Justify your answer.
Speed of sound in oxygen: 340 ms-1
Speed of sound in benzene: 200 ms-1
