AC Voltage Applied to a Capacitor

IMPORTANT

AC Voltage Applied to a Capacitor: Overview

In this topic, we will learn how to apply the AC voltage to a capacitor. It explains the capacitive reactance and amplitude to the current with a phase diagram. It talks about the charging and discharging of the capacitors.

Important Questions on AC Voltage Applied to a Capacitor

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Capacitor reactance is Xc in purely capacitive a.c circuit which is equal to 

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Phaser I makes with positive x-axis ( if voltage phaser E makes angle ωt with positive x-axis )

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Phase difference between current and voltage in purely capacitive a.c circuit is 

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The time constant of the circuit consisting capacitor C and resistance R is RC.

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The phase difference between the alternating current and emf is π2. Which of the following cannot be the constituent of the circuit ?

(a) LC

(b) L alone

(c) C alone

(d) R,L

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As the frequency of an AC circuit increases, the current first increases and then decreases. What combination of circuit elements is most likely to comprise the circuit?

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What is instantaneous power in purely capacitive circuit.

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Instantaneous power is defined as the limiting value of the average power when time tends to zero.

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Instantaneous power is defined as the limiting value of the average power when time tends to_____.

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No power loss associated with pure capacitor in ac circuit.

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The power consumed in a circuit element will be least when the phase difference in degree between the current and voltage is 

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Why power in a circuit is zero in which current and voltage are 90° out of phase?

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 When the supply frequency increases, what happens to the capacitive reactance in the circuit?

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A capacitor has capacitance C and reactance X. If capacitance and frequency becomes doubled, then reactance will be

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Which of the following curves correctly represents the variation of capacitive reactance XC with frequency f?

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Explain the term: Capacitive reactance.

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Role of capacitor in a circuit-

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A 60 μF  capacitor is connected to a 110 V rms, 60 Hz  ac supply. The rms value of current in the circuit is

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A 30 μF  capacitor is connected to a 150 V, 60 Hz  ac supply. The rms value of current in the circuit is

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In an alternating current circuit consisting of element in series, the current increases on increasing the frequency of supply. Which of the following elements are likely to constitute the circuit?