Magnets and Microphones

How does a Microphone work?

Did you know that there is more than one type of microphone? Microphones change one type of energy, sound energy, into another type, electrical energy. There are several ways to do this. The different types of microphones are:condenser microphones, wireless microphones and dynamic microphones. Condenser microphones use diaphragms to move a capacitor. A capacitor is an electric charge storing device. condenser microphones use those diaphragms and capacitors to generate a current. Wireless microphones (often called "radio mics"), on the other hand, use radio transmitters to send signals to amplifiers and work in that way. Dynamic microphones are the most common of microphones. They use diaphragms, magnets and coils to convert sound energy into electrical energy.
Dynamic Microphones are essentially the reverse of loud-speakers. They use the same parts, only they go "backwards", converting sound energy into electrical energy instead of converting electrical energy into sound energy.
Simple artwork showing how microphones work
Simple artwork showing how microphones work

To explain the diagram above: First, energy flow to the microphone in the form of sound energy. Second, the diaphragm, a thin piece of material that vibrates when it comes into contact with sound waves, in the head of the microphone vibrates. Thirdly, the coil vibrates as well, because it is connected to the diaphragm. Fourth, the permanent magnet in the microphone creates a magnetic field. An electric current flows through the coil as it vibrates within the magnetic field the permanent magnet creates. Lastly, the electric current that has been produced flo0ws out of the microphone and into an amplifing device, which will essentially reverse the process of the microphone to create sound energy again. Essentially, the sound energy goes through a circular process, starting as sound energy, becoming electric energy, and then returning again to sound energy as it exits the amplifier or recording device, depending on what the microphone is being used for.
Microphones, because of the process they use to convert acoustical (sound energy) energy into electrical energy are called tranducers. Transducers are simply devices that convert energy from one type to another.

The following is an informational video about the various different microphones that exist to date.

For more information on microphones go to:

Woodford, Chris. "How Microphones Work: Explain That Stuff!" Explain That Stuff! Science and Technology Made Simple. 2008. Web.
14 Mar.2011.

"How Do Microphones Work?" Media Wavelength Media. Web. 14 Mar. 2011.

"HowStuffWorks "5 Types of Microphones"" Howstuffworks "Electronics" Web. 17 Mar. 2011.