The ultrasonic sensor that comes with your Arduino kit is the HC-SR04. It consists of a high-frequency emitter, receiver and control circuit.
This sensor can provide non-contact distance measurements in the range from 2-400 cm.
When triggered, the unit sends out an 8 cycle burst of ultrasound at 40 kHz and “listens” for returning echos. The distance of a reflecting object is determined from the echo return time and the speed of sound.
See Elegoo Kit Lesson 10 for more details, including the Arduino sketch. The sketch makes use of the “SR04” library, which needs to be installed from the Elegoo tutorial files. A single function can then be used to trigger and return a distance measurement.
