Spaced Capacitor

An empty parallel plate capacitor is connected between the terminals of a 15.7-V battery and charges up. The c

An empty parallel plate capacitor is connected between the terminals of a 15.7-V battery and charges up. The capacitor is then disconnected from the battery, and the spacing between the capacitor plates is doubled. As a result of this change, what is the new voltage between the plates of the capacitor?

VC=Q
By doubling the distance, the capacitance will be halved and the voltage will double to 31.4 V. Note that the energy remains the same.
(As an aside, this is the -exact- principle that’s used in ‘varactor’ amplifiers)

Doug

All microphones convert sound energy into electrical energy, but there are many different ways to do the job, using electrostatics, electromagnetism, piezo electric effect or the change in resistance of carbon granules. The microphones are used in many applications, such as telephones, recorders, hearing aids, film production, audio engineering, live and recorded, on radio and television and computer for recording voice, VoIP, and acoustic purposes like ultrasonic checking.

When it comes to microphones used in music recording or live performances the vast majority of microphones used are condenser or dynamic or electrostatic or electromagnetic models. Both types employ a moving diaphragm to capture the sound, but make use of a different electrical principle for converting mechanical energy into an electrical signal. The efficiency of this conversion is very important, because the amounts of acoustic energy produced by the voices and musical instruments are so small.

Dynamic Microphones
Microphones dynamic work through electromagnetic induction. They are robust, relatively inexpensive and resistant to moisture, and therefore they are widely used on stage by singers. There are two basic types. The moving coil microphone and the ribbon microphone.

Dynamic microphones have the advantage of being relatively cheap and durable, and do not need a power supply or batteries to operate them. A lightweight diaphragm, usually of plastic film is attached a very small coil of wire suspended in the field of a permanent magnet. When a sound causes the diaphragm to vibrate, the whole assembly works as a generator miniature electricity, and produces an electric current minute. Because electricity production is very small, has to be amplified by a preamplifier microphone. Dynamic microphones are most effective when working with relatively strong sound sources that do not contain a lot of very high frequency details.

Condenser Microphones
Condenser microphones have existed for decades, and although modern techniques incorporate some minor improvements, the sound character has actually changed very little. Some of the best sounding capacitors have been designed over 20 years. The main part of the condenser microphone contains a pair of conducting plates, one fixed and the other in the form of a moving diaphragm. When the separation between the plates of the changes in capacity varies, and if a fixed electric charge is applied to the capacitor, an electrical signal that is produced, which faithfully represents the vibration of the diaphragm.

The capacitors are more expensive than their dynamic counterparts, but also much more sensitive, and can capture high frequency detail much more accurately. Moreover, the principle of capacitors, unlike the dynamic principle, lends itself easily to the production of microphones with interchangeable polar patterns, although models cheapest tend to offer only a fixed cardioid pattern.

Electret Microphones
An electret is a ferroelectric material that has been permanently electrically charged or polarized. An electret microphone is a relatively new type of capacitor microphone invented at Bell Labs in 1962. A static charge is embedded in an electret by alignment of static charges in the material, much the way a magnet is made by aligning the magnetic domains in a piece of iron. They are used in many applications, from high-quality recording and lavalier use to build small microphones recording devices sound and telephone.

About the Author:

Victor Epand is an expert consultant for music gear, speakers, and microphones. You can find the best marketplace for music gear, speakers, and microphones at these 3 sites: music gear, music equipment, speakers, and dynamic microphones, capacitor microphones, electret microphones.

Article Source: ArticlesBase.com – Varieties of Different Types of Microphones