Answer:
The radio wave that leaves a transmitting antenna originates as a sound spoken into a microphone. A microphone is a device for converting sound energy into electrical energy. A microphone accomplishes this transformation by any one of a number of mechanisms. In a carbon microphone, for example, sound waves entering the device cause a box containing carbon granules to vibrate. The vibrating carbon granules, in turn, cause a change in electrical resistance within the carbon box to vary, resulting in the production of an electrical current of varying strength.
