16. Sound

Sound is a form of energy which travel as waves. Sound waves are produced by objects that vibrate in a medium. The medium can be a gas, liquid or solid. A vibrating object produces sound waves by the shifting layers of air particles. The vibrating object pushes and...

Sound waves with frequencies above 20 kHz are called ultrasound, which exceeds the audible range for humans. Application In medical : Ultrasound is used to observe the internal parts of the body, especially in the development of a foetus. Ultrasound pulses are emitted...