Q. Why can we transmit the human voice via electric waves?

A. When we speak, air is vibrated. There is a diaphragm in a phone that can feel the vibration of the air. There is also a wire coil connected to the diaphragm, which is surrounded by a magnet. So when we speak, the coil moves inside the magnet. Then, according to the kind of voice or the movement of coil, electricity flows. The volume of this electricity is transmitted as a signal.