The capacitor offers zero resistance to AC only. Explain.

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A capacitor is a passive electrical component that stores energy in an electric field between two conductive plates separated by an insulating dielectric material. In an AC circuit, the voltage across a capacitor changes continuously with time, causing the capacitor to alternately charge and discharge as the current flows back and forth.

In an ideal capacitor, there is no resistance to the flow of AC current, but there is an opposition to any sudden change in voltage or current. The current in a capacitor at any instant is proportional to the rate of change of voltage across it. This current is called the displacement current and is given by the equation:

Id = ε0 * dV/dt

Where ε0 is the permittivity of free space and dV/dt is the rate of change of voltage with respect to time.

As the capacitor charges, the voltage across its plates increases, and the rate of change of voltage decreases. At the point when the capacitor is 50% charged, the rate of change of voltage is at its maximum, and therefore the displacement current is also at its maximum. As the capacitor continues to charge, the voltage across its plates approaches the value of the source voltage, and the rate of change of voltage decreases, causing the displacement current to decrease as well.

Therefore, a capacitor offers zero resistance to AC only, as the displacement current is the only current that flows through it, and it is not impeded by any resistance. In contrast, in a DC circuit, the capacitor acts as an open circuit, blocking the flow of current.

Capacitance in AC Circuits and Capacitive Resistance

Capacitance in AC Circuits and Capacitive Resistance

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The capacitor offers zero resistance to AC only. Explain.

CBSE CLASS XII Related Questions

1.
This ‘average velocity’ is found be few mm/s for currents in range of a few amperes. How then is current established almost the instant a circuit is closed ?

3.
Consider the nuclear reaction \( X \to Y + Z \). Let \( M_x \), \( M_y \), and \( M_z \) be the masses of the three nuclei X, Y, and Z respectively. Then which of the following relations hold true?

4.
With the help of a labelled diagram, explain the principle, construction and working of an a.c. generator.

Similar Physics Concepts

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The capacitor offers zero resistance to AC only. Explain.

CBSE CLASS XII Related Questions

1.This ‘average velocity’ is found be few mm/s for currents in range of a few amperes. How then is current established almost the instant a circuit is closed ?

3.Consider the nuclear reaction \( X \to Y + Z \). Let \( M_x \), \( M_y \), and \( M_z \) be the masses of the three nuclei X, Y, and Z respectively. Then which of the following relations hold true?

4.With the help of a labelled diagram, explain the principle, construction and working of an a.c. generator.

Similar Physics Concepts

Comments

SUBSCRIBE TO OUR NEWS LETTER

1.
This ‘average velocity’ is found be few mm/s for currents in range of a few amperes. How then is current established almost the instant a circuit is closed ?

3.
Consider the nuclear reaction \( X \to Y + Z \). Let \( M_x \), \( M_y \), and \( M_z \) be the masses of the three nuclei X, Y, and Z respectively. Then which of the following relations hold true?

4.
With the help of a labelled diagram, explain the principle, construction and working of an a.c. generator.