The telephone receiver is an accessory for transmitting sounds from telephones, walkie-talkies, mobile phones, and other communication tools. It is a type of speaker, but it is generally not called a speaker. The term is used generically to describe parts of an electronic product that transmit sound. Such as: mobile phones, walkie-talkies, and so on.
There will be a small film in the microphone and telephone receiver. The film in the microphone plays the role of the tympanic membrane in the person's ear. When you speak to it, the film will vibrate and the film will be connected to a small coil. (Note: This coil will follow the vibration of the film to change the position.), there is a small piece of permanent magnet fixed in the microphone (fixed in the microphone housing). The film is elastic and generally acts both as a vibration and as a pull back to the initial position. The film is attached to the microphone housing with one end attached to the coil.
When the film vibrates, the coil is driven to vibrate, and the relative position of the coil and the permanent magnet changes. This causes the magnetic field passing through the coil to change. When the magnetic field changes, an induced electromotive force is generated in the coil and a current is generated. Certain sounds have specific vibrations, and specific vibrations produce a specific form of current. So the microphone "codes" the sound into a current form.
The principle of the telephone receiver is probably the inverse of the microphone and its structure is almost the same. There is also a film in the telephone receiver, the film is connected to a coil, and there is also a permanent magnet. A specific form of current (such as the current that the microphone has just “coded”) flows through the coil of the handset, which causes the magnetic field generated by the coil to change, so that the magnetic force between the permanent magnet and the coil changes, so the distance between the permanent magnet and the coil It will change. This caused the film to vibrate and make a sound.