A loudspeaker is an electromagnetic device that is used to radios,televisions and speakers tom produce sound from an electric current.Like an electric motor,a loudspeaker also has a permanent magnet and a coil of wire around an iron rod.When an electric current passes through the wire,the permanent magnet pushes and pulls the electromagnet continously.The back an forth movements of the electromagnet causes the diaphragm vibrate nad make sound.