Capacitor & AC: Questions Answered

In summary, a capacitor is an electronic component that stores electrical energy in an electric field. It works by creating an electric field between two conductive plates separated by an insulating material. In an AC circuit, capacitors are used to block DC current and allow only AC current to pass through, as well as for energy storage, filtering, and improving power factor. The capacitance of a capacitor is calculated by dividing the electric charge on one of the plates by the potential difference between the plates. Capacitors can also be used in DC circuits for energy storage, filtering, and timing applications. However, they do not block DC current like they do in AC circuits.
  • #1
ragavcit
5
0
HI,
How come an AC flows through a capacitor when there is no continuity inbetween its plates??how come the resistance offered by a capacitor changes with frequency??
 
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  • #2
In 2 words: "displacement current". That should get you started.

Claude
 
  • #3
ragavcit said:
HI,
How come an AC flows through a capacitor when there is no continuity inbetween its plates??how come the resistance offered by a capacitor changes with frequency??

This should help as an introduction: http://en.wikipedia.org/wiki/Capacitor

And as I mentioned in your nearby Inductor thread, it's the "impedance" that changes with frequency, not its "resistance".
 

1. What is a capacitor?

A capacitor is an electronic component that stores electrical energy in an electric field. It consists of two conductive plates separated by an insulating material, known as a dielectric.

2. How does a capacitor work?

When a voltage is applied to a capacitor, the electric field between the plates is created and electrical energy is stored. The amount of energy stored is directly proportional to the voltage and the capacitance of the capacitor.

3. What is the purpose of a capacitor in an AC circuit?

In an AC circuit, a capacitor is used to block DC current and allow only AC current to pass through. It can also be used to store energy and release it at a specific time, to filter out unwanted frequencies, and to improve the power factor of the circuit.

4. How is the capacitance of a capacitor calculated?

The capacitance of a capacitor is calculated by dividing the electric charge on one of the plates by the potential difference between the plates. It is measured in Farads (F) and can range from picoFarads (pF) to Farads (F).

5. Can capacitors be used in DC circuits?

Yes, capacitors can be used in DC circuits, but their behavior is different compared to AC circuits. In DC circuits, capacitors can be used for energy storage, filtering, and timing applications. However, they do not block DC current like they do in AC circuits.

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