How does a Microphone work?
Microphone and its working
A microphone is a device which converts sound waves into electrical signals. These signals can then be broadcast through the air or sent over to distant points, where they can again be converted back into sound. Microphone can be divided into two groups depanding upon how they respond to sound waves. These are the pressure type and the velocity type. The pressure type Microphones contain a thin metal plate called a diaphragm. This is streched like a drumhead inside a rigid frame. When the sound waves strike the diaphragm, it starts vibrations at the same rate as the sound waves. These vibrations produce corresponding electric signals by changing the electric current that flows through the circuit. In the condenser microphone the vibrating diaphragm changes the capacitance of a condenser.
As the diaphragm vibrates in response to the sound the coil slids up and down the centrepiece of an M shaped permanent magnet. The coil thus cuts through the magnetic lines of force which induce a fluctuating voltage represents the variations in sound pressure. Crystal microphones make use of piezoelectric effect. Whenever certain crystal such as quartz are bent or twisted they generate an electric voltage. A carbon microphone works like a telephone transmitter. In this carbon granules varies the current to create a signal. Ribbon microphones have a metal ribbon instead of coils. The first practical microphone however was envented in 1878 by David Edward Hughes of United states. Other inventors of the microphone are Emaile Berliner Philip mReis Franus Blake and Henry Hunnings.