A simple buzzer is an electromechanical device that generates a buzzing or humming sound when an electrical current flows through it. It consists of a few basic components, including a coil of wire (electromagnet), a diaphragm or membrane, and a contact mechanism. Here's how it works:
Electromagnet (Coil of Wire): At the core of the buzzer is a coil of wire, which acts as an electromagnet. When an electric current passes through the coil, it generates a magnetic field around it. The strength of this magnetic field depends on the amount of current flowing through the coil.
Diaphragm or Membrane: Connected to the electromagnet is a diaphragm or membrane, often made of thin and flexible material such as metal or plastic. This diaphragm is free to move back and forth.
Contact Mechanism: The diaphragm is positioned close to a contact mechanism. This mechanism typically consists of a stationary contact and a movable contact attached to the diaphragm. When the diaphragm moves due to the magnetic forces generated by the electromagnet, it causes the movable contact to either make or break contact with the stationary contact.
Cycle of Operation: When an electrical current flows through the coil (electromagnet), it creates a magnetic field that attracts the diaphragm towards the coil. This movement causes the movable contact on the diaphragm to come in contact with the stationary contact, completing the electrical circuit. As the current continues to flow, the magnetic field remains strong, and the diaphragm remains attracted to the coil.
Sound Generation: However, as the diaphragm makes contact with the stationary contact, it completes a circuit that allows the current to flow through the coil. This results in a change in the magnetic field strength, which in turn affects the force attracting the diaphragm. As the diaphragm is pulled back slightly by the electromagnet's force, the movable contact loses contact with the stationary contact, breaking the circuit.
Repetition: With the circuit broken, the electromagnetic force on the diaphragm decreases, allowing the diaphragm to return to its original position due to its own elasticity. As it moves back, the movable contact makes contact with the stationary contact again, closing the circuit and repeating the process.
Buzzer Sound: This rapid opening and closing of the circuit, driven by the movement of the diaphragm caused by the changing electromagnetic force, results in a series of pulses of electric current. These pulses of current cause the diaphragm to vibrate back and forth at the same frequency, which produces an audible buzzing sound in the surrounding air.
In essence, the buzzing sound you hear from a simple buzzer is the result of the repeated opening and closing of an electrical circuit due to the interaction between the electromagnet, the diaphragm, and the contact mechanism.