How does the telephone handset work?
The handset contains both the ear-piece that you hold to your ear, and the mouthpiece, which is the part into which you speak. The mouthpiece is like the ear of the telephone. It hears what you say and converts these sounds into electricity. The ear-piece is like the mouth of the telephone — it converts the electrical signals into sounds that you hear. In a telephone, sound waves produced by a person’s voice exert pressure on a thin metal plate called a diaphragm, which vibrates and presses on carbon granules in the mouthpiece. When the carbon granules are pressed, the flow of the electrical current from the telephone exchange changes as it passes along the wire. The changes in the current form an electrical “pattern” of the voice. At the receiving end, the electrical signals flow through a coil in the ear-piece of the telephone. The coil is wrapped around a soft iron core and forms an electromagnet. When the current passes through the coil, it creates a magnetic field which causes a
