When you go on an expedition to mountains, you must have experienced the echo phenomenon while shouting loudly towards high mountains. You can even experience this phenomenon in a hall that doesn't have interiors such as curtains and furniture (in a new house). The ultrasonic sensor works on a similar principal. Ultrasonic sensors generate ultrasound waves that are targeted towards an obstacle after which they wait for the echo to be heard. However, why don't you hear any sound when you use an ultrasonic sensor? The answer is pretty simple: this sensor works at an ultrasonic frequency, which is higher than the audible frequency range of humans. The human's average theoretical audible frequency range is 20 Hz to 20 KHz. The ultrasonic sensor transmits the sound waves (also called as a sonic burst) higher than 20 KHz frequency. Ultrasonic waves are mainly used because they are not audible to the human ear and also because they provide precise distance measurement...