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Explain by giving a scientific reason. We cannot hear the echo produced in a classroom. - Science and Technology

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प्रश्न

Explain by giving a scientific reason.

We cannot hear the echo produced in a classroom. 

टीपा लिहा
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उत्तर

  1. An echo is a sound produced when the original sound is reflected by the walls of a given room. For instance, in a small room If there are hard walls there will be an echo of sound bouncing off the wall but because the sound bouncing is so close to the original, it is harder to detect the echo produced.
  2. A room which is having a dimension greater than 17.2 m will produce an echo in that room.
  3. The dimensions of a classroom usually do not exceed 17.2 m, so echo is not produced in a classroom. So, in the case of a classroom, no echo is produced in a classroom.
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पाठ 12: Study of Sound - Exercise [पृष्ठ १३७]

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बालभारती Science and Technology [English] 9 Standard Maharashtra State Board
पाठ 12 Study of Sound
Exercise | Q 2. c. | पृष्ठ १३७

संबंधित प्रश्‍न

An echo returned in 3 s. What is the distance of the reflecting surface from the source, given that the speed of sound is 342 m s−1?


Does sound follow the same laws of reflection as light does? Explain.


What is meant by an echo?


Explain why, the flash of lightning reaches us first and the sound of thunder is heard a little later.


Name three devices which work on the reflection of sound.


Why do we hear more clearly in a room with curtains than in a room without curtains ?


The echo of a sound is heard after 5 seconds. If the speed of sound in air be 342 m/s, calculate the distance of the reflecting surface.


The speed of sound in water is 1500 metres per second. How far away from an under-sea rock should a deep sea diver be so that he can hear his own echo ?


What is an echo ? How is echo formed ?


What is the minimum distance in air required from a sound reflecting surface to hear an echo (at 20°C) ?


A man standing 825 metres away from a cliff (steep rock) fires a gun. After how long will he hear its echo ? Speed of sound in air is 330 m/s.


State two conditions necessary for hearing an echo.


What are the medical applications of echo?


How can you calculate the speed of sound using 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.


Answer the following question in your own words. 

What factors are important to get a distinct echo?


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


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