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Which type of dielectric is used most often in variable capacitors?
Wiki User
∙ 14y ago
The type of dielectric most often used in variable capacitors is air. Also, trimmer capacitors often use mica.
Wiki User
∙ 14y ago
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What is the polarity of fixed capacitor?
Most fixed capacitors, and almost all variable ones, have no polarity. That is, itmakes no difference to the capacitor which side you make positive and which sideyou make negative, and your choice has no impact on the performance or lifetimeof the capacitor.Electrolytic capacitors and some tantalum ones do have a preference, and thepolarity of their two leads is marked on the component. Their dielectric is formedby an internal electro-chemical process that depends on the polarity, such thatthe dielectric goes away if the polarity is reversed, and then you no longer havea capacitor.
What is the difference between polar capacitors and bipolar capacitors?
Polar capacitors are acidic wet dielectric type capacitors which work only when there is a DC voltage present between its two leads in right polarity. Polar capacitors are ideally suited for a DC power supply ripple filter. When connected in wrong polarity, chemical reactions within a polar capacitor can cause them to blow up, often violently, causing injury to someone nearby. Most polar capacitors these days come with a safety valve to release internal pressure build up. Non polar capacitors are usually dry types made of ceramic, mylar, polyester or any possible dry insulator as a dielectric. Two polar capacitors connected back to back also make a non-polar capacitor. They work well in all situations whether there is any DC voltage present between their leads or not. Non polar capacitors are often very large and impractical in most applications except where a small capacitance value is required. Some good applications for non-polar capacitors are: an AC motor starter, an AC line spike filter and a crossover network. Since voltages across an AC motor or inside a speaker system consist only of pure AC, polar capacitors cannot be used in those cases. Polarized capacitors are typically large devices known as electrolytic or tantalum type packages, used for filtering or stabilizing voltage sources, usually in DC type circuits. Construction of these is if I recall correctly, an aluminum foil called the anode (positive lead), separated by an oxide film with a dielectric material known as the cathode (negative lead), hence polarity. Non-polarized are similar to polarized except the plates are similar metal. Polarized caps are typically used in large voltage situations, such as DC line filtering to reduce noise related to uneven voltage levels after rectification from an AC source. Mainly measured in microfarads. Polarity is critical to these devices. They are marked with the voltage rating (usually double the circuit voltage used) as well as the farad marking. non-polarized caps are typically used in low voltage situations, both AC and DC. Polarity is not critical. Measured in pico farads typically.
What is Dielectric grease used for?
It's supposed to be non-conductive yet it transfers heat. Dielectric grease is often used with a heat-sink to transfer the heat better and it can also be used in applications where electrical components might get damp and/or hot and corrode. Most auto manufacturers are using dielectric grease or other grease compounds to protect light sockets and other electrical connections.
What capacitors are polarity sensitive?
While most electrolytic capacitors are the ones that have a polarity noted as minus "-" and "+" as opposed to ceramic or film capacitors, it's important to note that even electrolytic capacitors could also be labelled as "np" for non-polarized or "bp" bi-polarized, which means the same thing, that there is no plus or minus and the current can flow in both directions. Today a good quality electrolytic, most of the time, will be another color to depict this such as green for example, whereas in older circuits they could sometimes look identical but just be missing the little "-" indicator. So, you need to pay attention to this little detail on older boards when replacing a capacitor.
What does a capacitor look like?
The physical appearance varies depending on the type of capacitor in question. The main similarity between the different types is that they have two leads.Electrolytic Aluminum Capacitors come as metal cans in appearance, and can be radial (both leads at the bottom) or axial (one lead at the top, one lead at the bottom). This type of capacitor is also polarized and typically will have a symbol indicating which lead should be connected to ground (most common) or a symbol for the lead that connects to the voltage source. Typically there will be a capacitance rating in Farads on the capacitor.Ceramic Capacitors come in many different appearances, one commonly found is a disc shape. These capacitors are not polarity sensitive and thus have no markings indicating polarity. They are smaller than Electrolytic Capacitors and usually do not have enough space to display a Farad rating but will use a numeric code (similar to color bands on resistors)There are many other types of capacitors and also "homebrew" capacitors composed of soda bottles and tin foil, which makes giving an exact answer to "What does a capacitor look like?" difficult.
What is an Air dielectric capacitor?
Capacitors are, in principal, two parallel plates separated by something (the dielectric). This dielectric can be many things, in fact most non-conductive things, air is just one. Warning, heavy science (way way above my level) http://en.wikipedia.org/wiki/Dielectric#Some_practical_dielectrics Photo of variable air dielectric capacitor, used to be used to tune radios for example. You can see the plates and air gap. http://en.wikipedia.org/wiki/File:Variable_Capacitor.jpg G
What is the polarity of fixed capacitor?
Most fixed capacitors, and almost all variable ones, have no polarity. That is, itmakes no difference to the capacitor which side you make positive and which sideyou make negative, and your choice has no impact on the performance or lifetimeof the capacitor.Electrolytic capacitors and some tantalum ones do have a preference, and thepolarity of their two leads is marked on the component. Their dielectric is formedby an internal electro-chemical process that depends on the polarity, such thatthe dielectric goes away if the polarity is reversed, and then you no longer havea capacitor.
Do capacitors have internal resistance?
1. The capacitor has Lead resistance in series with the capacitor2. Since most capacitor use Dielectric and they have a leakage resistance and it is parallel to the Ideal Capacitor.
What is cylindrical capacitor?
A cylindrical capacitor is a type capacitor in which two conducting cylinders are used and the dielectric medium is placed in between them .The outer most cylinder is earthed .The capacitance of these capacitors are higher than other
What is the difference between polar capacitors and bipolar capacitors?
Polar capacitors are acidic wet dielectric type capacitors which work only when there is a DC voltage present between its two leads in right polarity. Polar capacitors are ideally suited for a DC power supply ripple filter. When connected in wrong polarity, chemical reactions within a polar capacitor can cause them to blow up, often violently, causing injury to someone nearby. Most polar capacitors these days come with a safety valve to release internal pressure build up. Non polar capacitors are usually dry types made of ceramic, mylar, polyester or any possible dry insulator as a dielectric. Two polar capacitors connected back to back also make a non-polar capacitor. They work well in all situations whether there is any DC voltage present between their leads or not. Non polar capacitors are often very large and impractical in most applications except where a small capacitance value is required. Some good applications for non-polar capacitors are: an AC motor starter, an AC line spike filter and a crossover network. Since voltages across an AC motor or inside a speaker system consist only of pure AC, polar capacitors cannot be used in those cases. Polarized capacitors are typically large devices known as electrolytic or tantalum type packages, used for filtering or stabilizing voltage sources, usually in DC type circuits. Construction of these is if I recall correctly, an aluminum foil called the anode (positive lead), separated by an oxide film with a dielectric material known as the cathode (negative lead), hence polarity. Non-polarized are similar to polarized except the plates are similar metal. Polarized caps are typically used in large voltage situations, such as DC line filtering to reduce noise related to uneven voltage levels after rectification from an AC source. Mainly measured in microfarads. Polarity is critical to these devices. They are marked with the voltage rating (usually double the circuit voltage used) as well as the farad marking. non-polarized caps are typically used in low voltage situations, both AC and DC. Polarity is not critical. Measured in pico farads typically.
Which type of conductors are used in capacitors?
The conductors in capacitors are typically made from thin plates (or foil) of very ductile metallic materials to get the most capacitance. These materials must also be inexpensive and widely available. Aluminum is typically the workhorse material for most conductors in capacitors. Tantalum is used as well for the Cathode plate. Silver is also appears in silver-mica capacitors, and are used for high-accuracy audio applications. I believe that Manganese Dioxide MnO2 is sometimes used, as well, for the anode plate. A capacitor is a passive electronic component consisting of a pair of conductors separated by a dielectric (insulator). When there is a potential difference (voltage) across the conductors, a static electric field develops in the dielectric that stores energy and produces a mechanical force between the conductors. An ideal capacitor is characterized by a single constant value, capacitance, measured in farads. This is the ratio of the electric charge on each conductor to the potential difference between them.
Why you use capacitors in lines?
Capacitors are connected in series with some lines (series compensated lines) and in parallel. Capacitors in parallel are used to prop up the voltage at that location by injecting reactive power onto the grid. Capacitors in series are used to cancel out some of the inductance of the line, which allows for more power to be transported through the line. Capacitors at load centers are often used for power factor correction, and are connected in parallel (line to ground). To achieve efficiency in a power delivery system it is most efficient to have the current and voltage in phase. Often the load is inductive hence the current lags the voltage (due to motors etc.). Capacitors are switched in and out of the transmission system to counteract this effect.
What is Dielectric grease used for?
It's supposed to be non-conductive yet it transfers heat. Dielectric grease is often used with a heat-sink to transfer the heat better and it can also be used in applications where electrical components might get damp and/or hot and corrode. Most auto manufacturers are using dielectric grease or other grease compounds to protect light sockets and other electrical connections.
Is the x or the y the domain in a function?
x is a letter often used as a variable. It can be in the range or the domain. However, in elementary algebra, the variable x is most often used for the domain and f(x) =y for the range.
What is the most common and costly type of ESD damage?
Oxid failure is the most common type of ESD damage. When the voltage across a dielectric region excesses its dielectric tolerances, the result is a puncture of the dielectric. Once the dielectric has been punctured, small amount energy will be enough to create a short circuit. A device, after dielectric breakdown, will usually exhibit lower breakdown voltage, increased, leakage current and increased noise but not a catastrophic failure
Where to buy dielectric grease?
Most auto parts stores sell it.
How many volts can a capacitor hold. what would be the formula for a capacitor that holds 100 volts?
The working voltage of a capacitor depends on the nature of the dielectric and its thickness. Most capacitors are marked on the case e.g. 500V wkg. or just 150V. Small components are colour coded; the code will tell you the capacitance, and the wkg voltage.
