Microphone

Introduction
A microphone is an example of a transducer, a device that changes information from one form to another means sound wave  into electrical signal.Microphones are used in many applications such as telephone , hearing etc for concert halls .
How is this Work?                                                                                                                               Sound information exists as patterns of air pressure; the microphone changes this information into electric signal.
Basically there are two type of microphone is uses.
1 Dynamic Microphone
2 Condenser Microphone

1.Dynamic Microphone

In the magneto-dynamic, commonly called dynamic, microphone, sound waves cause movement of a thin metallic diaphragm and an attached coil of wire. A magnet produces a magnetic field which surrounds the coil, and motion of the coil within this field causes current to flow. 

2.Condenser Microphone

In a condenser microphone, the diaphragm is mounted close to, but not touching, a rigid backplate (The plate may or may not have holes in it) . A battery is connected to both pieces of metal, which produces an electrical potential, or charge, between them.The amount of charge is determined by  the area of the diaphragm and backplate, and the distance between the two. This distance changes as the diaphragm moves in response to sound. When the distance changes, current flows in the wire as the battery maintains the correct charge. The amount of current is essentially proportioinal to the displacement of the diaphragm, and is so small that it must be electrically amplified before it leaves the microphone.