Ultrasonic waves are those sound waves whose frequency is

Ultrasonic waves are sound waves with frequencies higher than 20,000 Hz, which exceeds the upper range of human hearing. These waves are utilized in diverse fields due to their ability to penetrate materials, produce detailed images in medical diagnostics (ultrasound), and clean delicate objects through cavitation in industrial processes. They are also crucial in applications like sonar for underwater navigation and detecting objects. The high frequency of ultrasonic waves allows for precise control and manipulation in technological applications, enhancing their utility in various industries.

The correct answer to the frequency of ultrasonic waves is; option [C] more than 20 Kilo Hertz. This distinction is essential as it marks the threshold where sound waves transition from audible to ultrasonic, offering distinct advantages in fields requiring high-resolution imaging, non-destructive testing, and efficient cleaning processes.