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A capacitor consists of two plates separated from one another by an insulator. These plates are normally thin foil and can be sandwiched around a very thin insulator and wrapped into a small package. Since there is an insulator between the plates, DC connected to the two plates cannot flow as long as you do not exceed the breakdown voltage of the insulator. AC current is a different story. Because the insulator is very thin and the effective plate area is relatively large, a negative charge building up on one plate causes electrons to be repelled from the opposite plate, and as the charge on the first plate reverses and becomes positive, the electrons in the opposite plate are attracted back again. This results in a matching alternating current flow on the opposite side of the capacitor.

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13y ago
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8y ago

Current cannot pass through a dieletric material in a capacitor. In fact charge is induced at the second plate. In steady state no dc can flow. In transient terms a current flows but it doesn't pass through the capacitor itself, charge mearly builds up at the second plate. With ac this is happening multiple times a second and current reverses back and forth but doesn't pass thorugh the capacitor itself.

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14y ago

A capacitor appears as an open circuit to a DC signal, and will have a specific impedance to the AC signal depending on the AC signal frequency:

A capacitor's impedance = 1/(j*w*C), where j = i = imaginary number, and w = the frequency in radians.

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Q: How can a capacitor filter the AC and DC?
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What is the difference between with capacitor rectifier and without capacitor rectifier?

To know the difference between capacitor and non capacitor rectifiers one must study what is the function of filter part.the filter part consists of capacitors or inductors or combination of both. the output of a simple diode rectifier is pulsating dc which means it consists of both dc part and ac part. filters are used to remove the ac part from such an output. capacitor filter means that a capacitor is used for filtering out the ac part. non capacitor or inductor filter means that an inductor is used for filtering out the ac part. There is another type called pii filter where both inductor and capacitor are used. Pii filter is the best kind of filter available


Does a charged capacitor block DC or AC or both?

It blocks DC or it wouldn't be charged. It passes AC through it to ground or it wouldn't filter. But in the early days charged electrolytic capacitors were used as rectifiers or AM detectors.


Why capacitor used only in AC power system?

A capacitor is included in the circuit to act as a filter to reduce ripple voltage. ... filter circuitmay be built using two capacitors and an inductor: ...look at http://en.wikipedia.org/wiki/Reservoir_capacitor


Characteristics of a capacitor?

Block DC components and pass AC component


What is purpose of emmiter bypass capacitor in R-C coupled amplifier?

Emitter bypass capacitor is a capacitor which provide low impedance to AC and high impedance to DC . AC is shunt then only DC appears on RC and volage gain increses.

Related questions

What is the difference between with capacitor rectifier and without capacitor rectifier?

To know the difference between capacitor and non capacitor rectifiers one must study what is the function of filter part.the filter part consists of capacitors or inductors or combination of both. the output of a simple diode rectifier is pulsating dc which means it consists of both dc part and ac part. filters are used to remove the ac part from such an output. capacitor filter means that a capacitor is used for filtering out the ac part. non capacitor or inductor filter means that an inductor is used for filtering out the ac part. There is another type called pii filter where both inductor and capacitor are used. Pii filter is the best kind of filter available


Can you convert a DC motor to run on AC?

The easiest way would be to convert the AC power to DC by using a rectifier diode and a filter capacitor. In that way you can now run your DC motor on DC.


What capacitor blocks either ac or DC?

Always DC.


What happens when a capacitor is connected to a dc supply?

is it ? are you sure ? but i know so many circuit where capacitor is connected with ac supply . still , if u connected a capacitor to dc supply , then : 1. if it is in SERIES with the dc supply , it will block all the dc current as capacitor provides infinite resistance to dc current . application : where u want to block dc current.(simple high pass filter) 2. if it is in PARALLEL with the dc supply , it will not block dc current , but if any ac current comes out from the supply , the ac current will go through the capacitor , as capacitor provides small resistance to ac current. application : a) where u want to block ac current.(simple low pass filter) b) to filter the noise (ac components) of dc supply.


Why you use capacitor as a filter in power supply?

capacitor acts as a small battery ,during rectification ac to dc it gets some blank space (no current) to fill this current from capacitor is used.


Why a capacitor does not accept AC?

A capacitor conducts AC but do not conduct DC because it is meant to store charge.


Electric device blocks dc but allows ac?

A capacitor blocks DC but allows AC.


What is an electrical capacitor?

Electricity is either alternating current or direct current, abbreviated AC or DC. An AC/DC Capacitor can be used in either an AC or DC current.


Does a charged capacitor block DC or AC or both?

It blocks DC or it wouldn't be charged. It passes AC through it to ground or it wouldn't filter. But in the early days charged electrolytic capacitors were used as rectifiers or AM detectors.


Can we use AC capacitor in surge suppression circuit DC?

A capacitor is a capacitor, no matter what circuits you use it in. There is no difference between one used in AC and one in DC, except perhaps the size that is appropriate.


What devices can be used to block DC and pass AC?

simple capacitor can do this job (to block dc and pass ac).


Why capacitor used only in AC power system?

A capacitor is included in the circuit to act as a filter to reduce ripple voltage. ... filter circuitmay be built using two capacitors and an inductor: ...look at http://en.wikipedia.org/wiki/Reservoir_capacitor