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प्रश्न
Answer the following question in your own words.
What is an echo?
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उत्तर
An echo is the reflection of sound waves off a surface, such as a wall, mountain, or building, that returns to the listener after a delay. It occurs when the reflected sound reaches the ear after at least 0.1 seconds, allowing the listener to distinguish it from the original sound. Echoes are commonly experienced in large, empty spaces or near hard, smooth surfaces.
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संबंधित प्रश्न
When a sound is reflected from a distant object, an echo is produced. Let the distance between the reflecting surface and the source of sound production remains the same. Do you hear echo sound on a hotter day?
What is meant by an echo?
The minimum distance between the source and the reflector in air. So that an echo is heard is approximately equal to ______.
Which of the following statement best describes frequency?
Name three devices which work on the reflection of 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.
Why are the ceilings of concert halls made curved ? Draw a labelled diagram to illustrate your answer.
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 the minimum distance in air required from a sound reflecting surface to hear an echo (at 20°C) ?
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 ?
Which of the following device does not work on the multiple reflections of sound waves ?
Answer the following question in your own words.
Study the construction of the Golghumat at Vijapur and discuss the reasons for the multiple echoes produced there.
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 an echo?
How can you calculate the speed of sound using echo?
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?
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
