Ultrasound

What is Ultrasound?

Ultrasound is sound with a frequency higher than 20 kHz, above the upper limit of human hearing; it is used in cleaning, in prenatal and other medical scanning, and in sonar for measuring depth and distance.

This definition is part of the Waves chapter in Cambridge O Level Physics.

Concepts related to Ultrasound

• audible range
• sonar
• medical scanning
• echo

Common mistakes with Ultrasound

• 22. “Ultrasound means very loud sound.” Why wrongIt confuses the two axes of a trace. “Ultra” here refers to frequency, not amplitude. A dog whistle is ultrasonic and very quiet. CorrectUltrasound is sound of frequency above 20 kHz, beyond the upper limit of human hearing. Its loudness is a separate matter entirely. Say this“Ultrasound is sound with a frequency higher than 20 kHz.” CheckIs a 30 kHz sound necessarily loud? Explain.