This is an excerpt from a recent educational article by Banner:

Ultrasonic sensors are devices that generate ultra-high-frequency sound waves greater than 20 kHz, beyond the range of human hearing. They use electrical energy and a ceramic transducer, which both transmits and receives sound waves. Sound waves are essentially pressure waves that travel through solids, liquids and gases and can be used in industrial applications to measure distance or detect the presence or absence of targets.

The sensor has a ceramic transducer that vibrates when electrical energy is applied to it. The vibrations compress and expand air molecules in waves that travel from the sensor face to a target object. The ultrasonic sensor measures distance by emitting a sound wave and then “listening” for a set period of time, allowing for the return echo of the sound wave bouncing off the target, before retransmitting.

To read the complete article, click on this link:
https://www.bannerengineering.com/us/en/company/expert-insights/ultrasonic-sensors-101.html

Sincerely,

Julius Frago,
The Automation School