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प्रश्न
What is meant by an echo?
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उत्तर १
If a person stands at some distance from a wall or a hillside and produces a sharp sound, he hears two distinct sounds: one is original sound heard almost instantaneously and the other one is heard after reflection from the wall or hillside, which is called echo.
उत्तर २
The sound that keeps coming after reflecting off of a hard surface (such a cliff, a hillside, a building's wall, or the edge of a forest). It's referred to as an echo.
संबंधित प्रश्न
Name the device which is used to address a small gathering of people.
On which day, a hot day or a cold day, an echo is heard sooner ? Give reason for your answer.
In which medium, air or water, an echo is heard much sooner ? Why ?
An echo-sounder in a trawler (fishing boat) receives an echo from a shoal of fish 0.4 s after it was sent. If the speed of sound in water is 1500 m/s, how deep is the shoal ?
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 is an echo?
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?
What is the minimum distance needed for an 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.
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?
