How a telephone works

A telephone is telecommunications device that is used to transmit and receive sound, usually two people conversing but occasionally three or more people. It is one of the most common household appliances in the world today. Most telephones operate through transmission of electric signals over a complex telephone network which allows almost any phone user to communicate with almost anyone. In this essay I will show you a process how a telephone works.

First of all, when a person speaks into a telephone, the sound waves created by his voice enter the mouthpiece. An electric current carries the sound to the telephone of the person he or she is talking to. A telephone has two main parts that is the transmitter and the receiver. After that, the transmitter of a telephone serves as a sensitive “electric ear” which lies behind the mouthpiece of the phone. Like the human ear, the transmitter has a 14 eardrum. The eardrum of the telephone is a thin, round metal disk called a diaphragm. So when a person talks into the telephone, the sound waves strike the diaphragm and make it vibrate. The diaphragm vibrates at various speeds, depending on the variations in air pressure caused by the varying tones of the speaker's voice.

Then, behind the diaphragm lay a small cup filled with tiny grains of carbon. The diaphragm presses against these carbon grains. The low voltage electric current travels through the grains where the pressure on the carbon grains varies as sound waves make the diaphragm to vibrate. A loud sound causes the sound waves to push hard on the diaphragm. Hence, the diaphragm presses the grains tightly together so that it easier for the electric current to travel through and a large amount of electricity flows through the grains.

After that, when the sound is soft, it pushes lightly on the diaphragm. Therefore, the diaphragm puts only a light pressure on the carbon grains. The grains are pressed together loosely. This makes it harder for the electric current to pass through them, and less current flows through the grains. The pattern of the sound waves determines the pressure on the diaphragm. This pressure regulates the pressure on the carbon grains. The crowded or loose grains cause the electric current to become stronger or weaker. The current copies the pattern of the sound waves and travels over a telephone wire to the receiver of another telephone.

Next, the vocal cords of the receiver are a diaphragm. Two magnets located at the edge of the diaphragm cause it to vibrate. One of the magnets is a permanent magnet that constantly holds the diaphragm close to it. The other magnet is an electromagnet. It consists of a piece of iron with a coil of wire wound around it. When an electric current passes through the coil, the iron core becomes magnetized so that the diaphragm is pulled toward the iron core and away from the permanent magnet. The pull of the electromagnet varies between strong and weak, depending on the variations in the current. Thus, the electromagnet controls the vibrations of the diaphragm in the receiver.

More than that, the electric current passing through the electromagnet becomes stronger or weaker according to the loud or soft sounds. This action causes the diaphragm to vibrate according to the speaker's speech pattern. As the diaphragm moves in and out, it pulls and pushes the air in front of it. The pressure on the air sets up sound waves that are the same as the ones sent into the transmitter. The sound waves strike the ear of the listener and he or she hears the words of the speaker.

As I have described, you will know how a telephone works in communication system between one people to another people whether the distance is far or near.