Electrets are dielectric materials with a quasi-permanent electric field. They are used in condenser microphones and piezoelectric transducers to generate voltage proportional to sound. Electrets have strong electrostatic polarization and do not require an external voltage source.
An 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 hold a significant amount of strong electric field at the point where it was immersed when it was manufactured.
Electrets exhibit strong electrostatic polarization. This means that the potential held, in the form of electrostatic polarization, is similar to the way the magnetic polarization of ordinary permanent magnets used in school laboratories is held. The difference between an electret and a permanent magnet is that a permanent magnet has a quasi-permanent magnetic field, whereas electrets have a quasi-permanent electric field.
One use for electrets is to be the dielectric in a condenser microphone. In electrical circuit theory, a capacitor, usually referred to as a capacitor, is composed of two conductive plates separated by a dielectric material. A capacitor can be powered by charging it with a DC voltage source, such as an AA battery, to produce a positive electrical voltage on one plate and a negative voltage on the other. The capacitor usually holds the voltage for a long time, limited only by the characteristics of the insulator or dielectric between. It is now electrostatically polarized by the charging voltage.
When an electret replaces the dielectric in the condenser or condenser microphone, there is no need to provide an external voltage source to produce the electrostatic field because the electret already has an electrostatic charge. When the compression and expansion of the voice air “moves” the condenser microphone plates, a small but significant voltage is generated that is proportional to the voice or sound on the microphone. Electret microphones are used in many audio devices, such as portable media players and voice recorders.
The piezoelectric transducer also uses an electret in the form of ceramics with strong electrostatic polarization. There are two plates, one fixed and one plated on the dielectric. When an electrical signal in the audio spectrum of sufficient level is applied to both the fixed and movable plates, the movable plate vibrates at the same rate as that of the electrical signal. This type of electret transducer is capable of transforming electrical signals into audible sound and with speeds beyond audibility.
Protect your devices with Threat Protection by NordVPN
