What is Electret?
Electret is a material that has a static electric field. This word is a combination of "electricity" and "magnet". The material used in Electrets is a special dielectric, an insulator with a special ability to maintain a significant amount of powerful electric field where it was immersed at the time of its production.
Electlets show a strong electrostatic polarization. This means that the preserved potential in the form of electrostatic polarization is similar to the way the magnetic polarization of common permanent magnets used in school laboratories is maintained. The difference between Electret and the permanent magnet is that the permanent magnet has an almost permanent magnetic field, while electrical electrical electrical fields have. In the theory of the electrical circuit, the capacitor, usually referred to as a capacitor, consists of two conductive boards separated by dielectric material. The executor may be under voltage voltage, such as the Penlight battery to create a positiva electrical voltage on one board and negative voltage on the other side. The capacitor usually holds the voltage for a long time, only limited by the characteristics of the insulator or the dielectric between them. It is now electrostatically polarized by charging voltage.
If the electrical replace the dielectric in the capacitor or the microphone of the capacitor, there is no need to supply the external source of the voltage for the production of the electrostatic field, because Electret already has an electrostatic charge. When the air compression and the voice extension "moves" the condenser microphone board, a small but significant voltage that is proportional to the voice or sound on the microphone is created. Electret microphones are used in many sound devices such as portable media and voice recorders.
Piezoelectric converter also uses electret in the form of ceramics with strong electrostatic polarization. There are two boards, one of which is solid and one that is oncarried on dielectric. When the electrical signal in the sound spectrum is sufficiently sufficient to the fixed and movable plate, the moving plate vibrates at the same speed as the electrical signal. This type of Electret converter is able to transform electrical signals into sound sound and at speeds beyond audibility.