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प्रश्न
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उत्तर
The sound heard after reflection from a rigid obstacle (such as cliff, a hillside, a wall of a building, edge of a forest etc.), is called an echo.
Conditions necessary for echo formation are:
1. The minimum distance between the source of sound and its reflector should be 17 m.
2. Reflected sound should reach the person atleast 0.1 second after the original sound is heard.
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संबंधित प्रश्न
A wave passes from one medium to another medium. Mention one property of the wave out of speed, frequency or wavelength which does not change.
State two differences between the light and sound waves.
Draw a labelled diagram to show the multiple reflections of sound in a part of the stethoscope tube.
Define the term Frequency (as applied to sound waves)
Write the approximate value of the speed of sound in air.
What are fishing boats?
A type of electromagnetic wave has a wavelength of 50 Å. Name the wave and state one use of this type of wave.
(i) A man stands at a distance of 68 m from a cliff and fires a gun. After what time interval will he hear the echo, if the speed of sound in air is 340 ms−1?
(ii) If the man had been standing at a distance of 12 m from the cliff would he have heard a clear echo?
Explain reflection at the boundary of a rarer medium.
