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प्रश्न
What is ultrasound ? What is the difference between ordinary sound and ultrasound ?
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उत्तर
Ultrasound waves are high-frequency sound waves. Due to higher frequency, they can penetrate into matter to a large extent.
We can differentiate between ordinary and ultrasonic waves as :
| Audible sound waves | Ultrasound waves |
| They have a frequency range of 20 Hz–20,000 Hz | They have frequencies above 20,000 Hz |
| These sounds are audible to human ears. | These sounds are inaudible to human ears. |
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संबंधित प्रश्न
What is the audible range of the average human ear?
A person has a hearing range from 20 Hz to 20 kHz. What are the typical wavelengths of sound waves in air corresponding to these two frequencies? Take the speed of sound in air as 344 m s−1.
Name the organs of hearing in our body.
What name is given to the sound waves of frequency too low for humans to hear ?
What name is given to the sound waves of frequency too high for humans to hear ?
What is the difference between infrasonic waves and ultrasonic waves ?
Three different vibrating objects produce three-types of sounds X, Y and Z. Sounds X and Y cannot be heard by a man having normal range of hearing but sound Z can be heard easily. The sound X is used in hospitals to break kidney stones of a patient into fine grains which then get flushed out with urine. The sound Y is similar to that which is produced during an earthquake before the main shock wave is generated.
(a) What type of sounds are (i) X (ii) Y, and (iii) Z ?
(b) Name one device which can produce sound like X.
(c) Name one device in a science laboratory which can produce sound like Y.
(d) Name one device in our homes which can produce sound like Z.
(e) What is the frequency range of sounds like Z ?
One of the following can hear infrasound. This one is :
Which of the above two graphs (a) and (b) (Fig.12.3) representing the human voice is likely to be the male voice? Give a reason for your answer.
A girl is sitting in the middle of a park of dimension 12 m × 12 m. On the left side of it, there is a building adjoining the park and on the right side of the park, there is a road adjoining the park. A sound is produced on the road by a cracker. Is it possible for the girl to hear the echo of this sound? Explain your answer.
