Many useful devices today use on the or sound to transmit energy or information quickly, reliably and efficiently. radio waves are used to carry information from a broadcaster to your home. the information is sent in the form of and is converted into electrical impulse by your radio. these electrical impulse are then converted into by the use of a speaker or your earphones. wireless technology, such as your cell phone or other wifi devices also use radio waves or microwaves to transmit and information quickly. another use of waves is in ultrasound. are reflected off tissues with different densities. the or echo is then detected by the machine and a picture is generated from these reflected sound waves. these pictures can show the development of a fetus in a pregnant woman or to look for a possible injury in a person.