Question

Ultrasound has frequency of vibration
(a) between 20 and 20,000 Hz
(b) below 20 Hz
(c) above 20,000 Hz
(d) between 500 and 10,000 Hz


NCERT Class VIII
Science - Exemplar Problems

Chapter 13. Sound

Answer 1

Ultrasound has frequency of vibration above 20,000 Hz . So , Option (c) is correct .

Answer 2

Answer: The correct answer is option c that is Ultrasound has frequency of vibration above 20,000 Hz

Explanation:

• Higher frequency sound waves than the upper audible range of human hearing are referred to as ultrasound and the only physical difference between ultrasound and "regular" (audible) sound is that humans cannot hear it.
• This limit varies from person to person and, in healthy young people, is around 20 kilohertz (20,000 hertz).
• Operating frequencies for ultrasound equipment range from 20 kHz to several gigahertz.
• Numerous industries employ ultrasound. Distance measurements and object detection are both done with ultrasonic equipment. In medicine, sonography and ultrasound imaging are frequently employed.
• Ultrasound is used to find hidden faults in products and structures during nondestructive testing.
• In the workplace, ultrasound is used to speed up, mix, and clean up chemical processes. Animals that use ultrasound for navigation include bats and porpoises.

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