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प्रश्न
What is an echo ? How is echo formed ?
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उत्तर
The repetition of sound caused by the reflection of sound is called echo. An echo is produced when sound is reflected from a hard surface such as a tall brick wall or a cliff.
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?
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.
What is the other name of a loud-hailer ?
Name the device which is used to address a small gathering of people.
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.
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 meant by 'reflection of sound' ? What type of surfaces are the best for reflecting sound ?
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.
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 ?
Which of the following device does not work on the multiple reflections of sound waves ?
A man is standing between two vertical walls 680 m apart. He claps his hands and hears two distinct echoes after 0.9 seconds and 1.1 seconds respectively. What is the speed of sound in the air?
State two conditions necessary for hearing an echo.
What are the medical applications of echo?
______ allows bats to navigate through dark caves and find insects for food.
______ is an image obtained by the use of reflected ultrasonic waves.
