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प्रश्न
Explain by giving a scientific reason.
We cannot hear the echo produced in a classroom.
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उत्तर
- 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.
- A room which is having a dimension greater than 17.2 m will produce an echo in that room.
- 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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संबंधित प्रश्न
What is meant by an echo?
Name three devices which work on the reflection of sound.
What is the other name of a loud-hailer ?
Fill in the blank with suitable word :
An echo is simply a ................... sound.
Fill in the blank with suitable word :
Echoes are caused by the ...................... of sound.
On which day, a hot day or a cold day, an echo is heard sooner ? Give reason for your answer.
Name any two objects which are good reflectors of sound.
State the laws of reflection of sound.
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.
A man is kidnapped, blindfolded and imprisoned in a big room. How could the man tell if he was in : a furnished room
The frequencies of four sound waves are given below. Which of these sound waves can be used to measure the depth of sea by the echo method ?
Answer the following question in your own words.
What should be the dimensions and the shape of classrooms so that no echo can be produced there?
How can you calculate the speed of sound using echo?
To hear an echo, the minimum distance of the obstacle from the source of sound must be ______.
______ is an image obtained by the use of reflected ultrasonic waves.
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?
Answer the following question in your own words.
What factors are important to get a distinct echo?
