why silver mica capacitors are used in H.F.?
916005
Mica dielectric has a very low loss and has a fairly stable capacitance at even VHF.
277811
Large Capacitor banks is one way.\n\nRegenerative Drives which take lost energy and feed it back in to the power grid has become much more popular based on the embeded logic controllers.\n\nInduction machines are terrible regarding power factor. Todays electronics has greatly improved the power factor loss.
1186584
The hotter the surface gets the more resistance. It is a solid state item.
248008
Pure silver is nearly white, lustrous, soft, very ductile, malleable, it is an excellent conductor of heat and electricity. It is not a chemically active metal, but it is attacked by nitric acid (forming the nitrate) and by hot concentrated sulfuric acid. It has the highest electrical conductivity of all metals, but its greater cost has prevented it from being widely used for electrical purposes.\n\nSilver is almost always monovalent in its compounds, but an oxide, a fluoride, and a sulfide of divalent silver are known. It does not oxidize in air but reacts with the hydrogen sulfide present in the air, forming silver sulfide (tarnish). This is why silver objects need regular cleaning. Silver is stable in water.\n\nProperties\n----------\nAtomic number 47\nAtomic mass 107.87 g.mol -1\nElectronegativity according to Pauling 1.9\nMelting point 962 °C\nBoiling point 2212 °C\nVanderwaals radius 0.144 nm\nIonic radius 0.126 nm\nIsotopes 11\nElectronic shell [ Kr ] 4d10 5s1\nEnergy of first ionization 758 kJ.mol -1\nEnergy of second ionization 2061 kJ.mol -1\nDiscovered by The ancients\n\nDensity of solid [/kg m-3]: 10490  \nMolar volume [/cm3]: 10.27  \nVelocity of sound [/m s-1]: 2600  \n\nElastic properties\nYoungs modulus [/GPa]: 83  \nRigidity modulus [/GPa]: 30  \nBulk modulus [/GPa]: 100  \nPoissons ratio [no units]: 0.37  \n\nHardnesses\nMineral hardness [no units]: 2.5  \nBrinell hardness [/MN m-2]: 24.5  \nVickers hardness [/MN m-2]: 251  \n\nElectrical properties\nElectrical resistivity [/10-8 Ω m; or mΩ cm]: 1.6  \n\nReflectivity [/%]: 97
842836
The best answer you can get is by going to howstuffworks.com. They have a very detailed description.\n\nBut basically, capacitors store electric energy and release it when it is needed most. A capacitor has two metal plates inside it, to hold the charge, and a material called a dielectric, which could be just about anything that is non-conductive, to keep the plates from touching each other. (I think that's what you were asking about the material between the capacitor.)\nThe one plate connected to the positive power loses electrons to the power source, and the other is connected to the negative, and gains electrons, thereby becoming electrically charged.\nA capacitor can be used to smooth out a DC voltage, supply extra power to a motor on start-up, or a large number of other things.\nBy the way, capacitance is measured in Farads, or, more commonly, micro-farads, nano-farads and pico-farads, which are very small parts of a farad. 10 to the power of -6, -9, and -12, respectively.
897898
An active filter is a type of analog electronic filter, distinguished by the use of one or more active components i.e. voltage amplifiers or buffer amplifiers. Typically this will be a vacuum tube, transistor or operational amplifier.\n\nThere are two principal reasons for the use of active filters. The first is that the amplifier powering the filter can be used to shape the filter's response, e.g., how quickly and how steeply it moves from its passband into its stopband. (To do this passively, one must use inductors, which tend to pick up surrounding electromagnetic signals and are often quite physically large.) The second is that the amplifier powering the filter can be used to buffer the filter from the electronic components it drives. This is often necessary so that they do not affect the filter's actions.\n\nPassive filters:\n\nSingle pole types:\nThe simplest electronic implementations of linear filters are based on combinations of resistors, inductors and capacitors. These filters exist in so-called RC, RL, LC and RLC varieties. All these types are collectively known as passive filters, because they do not depend upon an external power supply. Inductors block high-frequency signals and conduct low-frequency signals, while capacitors do the reverse. A filter in which the signal passes through an inductor, or in which a capacitor provides a path to earth, therefore presents less attenuation to low-frequency signals than high-frequency signals and is a low-pass filter. If the signal passes through a capacitor, or has a path to ground through an inductor, then the filter presents less attenuation to high-frequency signals than low-frequency signals and is a high-pass filter. Resistors on their own have no frequency-selective properties, but are added to inductors and capacitors to determine the time-constants of the circuit, and therefore the frequencies to which it responds.\n\nAt very high frequencies (above about 100 megahertz), sometimes the inductors consist of single loops or strips of sheet metal, and the capacitors consist of adjacent strips of metal. These are called stubs.
530979
http://www.mic-innovations.com/drivers.cfm
930867
Capacitors = stored energy, leaking dieletric (if hazardous), and/or reverse polarity may cause rupture/failure. Over-voltage can cause failure also. Always store de-energized and shorted.\n\nInductors = No hazard if de-energized. Inductors in service with an over-current condition can overheat and cause burns or failure of the component.
441296
In certain low volume and high speed circuits, transistors will always have their places. ALthough their are now many more radio chips.\nMIKE
688125
This is a good question.  Many of the electronic devices today use semi-conductor devices that work at low voltages.  However, that has only been the case since the mid-1960's on average.  Prior to this electronic devices used Vacuum Tubes.  These vacuum tubes used very high voltage DC to cause the flow from an cathode to an anode to flow.\n\nUntil the development of the High Voltage semi-conductor or Silicon Diode most electronics circuits used Vacuum Tube Diodes.  These Diodes would allow for current to flow in only one polarity the same as silicon diodes.\n\nAn intermediate high voltage diode between the vacuum tube diode and the silicon diode was the Selenium Diode.  This diode was the first solid state diode; however, they were not very efficient nor were very effective when high currents were required.  However, today selenium diodes are still in use where size is not an issue.  These diodes generally can work with voltages up to about 2000 VAC and currents as high as 100 amps.\n\nGenerally, most high voltage circuits today use silicon diodes with a high Peak Inverse Voltage (PIC).  On average most cost effective Silicon diodes have a PIV of 600 volts DC.  To increase the voltage that diodes can work you can put them in series, or connected one after then other.  This way you can daisy chain several diodes together to achieve a PIV of up to around (3 in a row) or 1800 volts before the capacitance could be a problem.  This same type of diode works at one amp, if you place them in parallel or side by side you can increase the amount of current your bridge can support.  Again I would not recommend using more then 3 semi-conductor or silicon diodes in parallel, or use for rectifying more 3 Amps of voltage.\n\nTo make your Neon Sign DC voltage converter I would recommend using selenium diodes specifically designed for the high voltage you are talking about.  These diodes and semi-conductor diodes are still available from a number of retail suppliers.  If you would like to try a Vacuum Tube diode, similar to the one used in the high voltage section of a Color TV, Ratheon is the only supplier I can recall that still makes vacuum tube diodes.
165187
Glass, teflon, bakelite and ceramics are among the best insulators.\n\nSilver is the best conductor of electricity, followed by copper.  Note that gold is often used for electrical contacts  NOT because it is the best electrical conductor, but because it is perhaps the least chemically reactive of metals.\n\nSeveral corrections to an answer below:\n\n1. Gold is a better conductor than aluminum. \n2. Air and vacuum are relatively poor electrical insulators, not even close to being the best. \n3. A glass insulator is 100 times better than either air or vacuum, and 1.3 to 2 times better than teflon. \n4. Mica is an even better insulator: 250 times better than air, and 2.6 times better than teflon.
177692
No matter what is the voltage rating, isolation or insulation is tested by using "MEGGER".\nThe value should be atleast above 1 Mega ohm in any case
441850
In soldering of metals, flux serves a threefold purpose: \n\nremoves oxidation from the surfaces to be soldered \n\nseals out air thus preventing further oxidation\n\nfacilitating amalgamation improves wetting characteristics of the liquid solder.
326662
This is (or was) referred to as "Band 2 VHF"  The other VHF bands being used for purposes other than public broadcast. VHF being "very high frequency", higher than HF (= Short-wave) but lower than UHF (Ultra high frequency, as used for example by normal television transmission) \nIf by "Why?", you mean "Why was this frequency selected for this purpose?" I have no expert knowledge, but presume it was a useful trade-off between the bandwidth required for FM audio transmission, and the area a transmitter could cover effectively.
1066864
If you think about it, the capacitance is the ability to store charge, so that leads me to conclude:\n1)It is has a positive correlation to the concentration\n2)It's limited by the size of the double layer.  If you have a small area  that the double layer is building up on(small electrode)-it'll reach the maximum and then stop being able to increase capacitance despite concentration much faster than if it's a large electrode.\nSo, I'm guessing, it is something like, the change in capacitance (not the capacitance itself) due to the change in concentration increases until it reaches a limit imposed by the area of the electrode.\nIt's just qualitative, but you said you didn't mind.
241115
Electrolytic capacitors consist of two elements, the isolation material Aluminium oxide as one plate and an electrolyte-soaked paper (some modern types are even virtually solid) as the other plate.\n\nA second sort are Tantalum capacitors\nTantalum electrolytic capacitors exploit the tendency of tantalum to form a protective oxide surface layer, using tantalum foil as one plate of the capacitor, the oxide as the dielectric, and an electrolytic solution as the other plate. Because the dielectric layer can be very thin (thinner than the similar layer in, for instance, an aluminium electrolytic capacitor), a high capacitance can be achieved in a small volume.
723475
The reason polarity matters in an electrolytic capacitor is because the dielectric(the insulator between the two conducting plates) was manufactured by passing a direct current to a metal plate immersed in an electrolytic solution.   If you feed a current in the opposite direction through the capacitor, you'll destroy the dielectric.   If it's a large current the capacitor will explode.   Other types of capacitor can handle current in either direction.