AC Through Capacitor

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What is the role of a capacitor in an AC circuit?

In an AC circuit, a capacitor allows the AC current to pass while blocking DC current. It also causes a phase shift between voltage and current.

How does the reactance of a capacitor change with frequency?

The reactance (Xc) of a capacitor decreases as the frequency of the AC signal increases. It is given by the formula Xc = 1 / (2πfC).

What is the unit of capacitive reactance?

The unit of capacitive reactance is Ohms (Ω).

Explain the phase difference between current and voltage in a capacitive AC circuit.

In a capacitive AC circuit, the current leads the voltage by 90 degrees.

What mathematical expression represents the capacitive reactance?

The capacitive reactance (Xc) is given by Xc = 1 / (2πfC), where f is the frequency and C is the capacitance.

What happens to the impedance in a circuit with only a capacitor when frequency increases?

The impedance decreases as frequency increases in a circuit containing just a capacitor.

Describe what a phase angle in an AC circuit with a capacitor means.

The phase angle in a capacitive AC circuit indicates that the current leads the voltage by a specific degree, usually 90 degrees.

How can you calculate the total voltage across capacitors connected in parallel?

For capacitors in parallel, the total voltage across each capacitor is the same as the source voltage.

Explain why capacitors are used in AC circuit filters.

Capacitors in AC circuit filters block low-frequency signals while allowing high-frequency signals to pass, useful for filtering specific frequencies.

What is the impact of increasing the capacitance in an AC circuit?

Increasing the capacitance in an AC circuit decreases the capacitive reactance, allowing more current to flow.

How does a capacitor behave differently in AC and DC circuits?

In DC circuits, a capacitor blocks current once fully charged, while in AC circuits, it continuously allows the alternating current to flow.

What is the formula for capacitive reactance in terms of angular frequency?

The capacitive reactance Xc = 1 / (ωC), where ω is the angular frequency (ω = 2πf).

What happens to current amplitude when capacitance is doubled in an AC circuit?

When capacitance is doubled, the current amplitude doubles, assuming a constant voltage and frequency.

How do capacitors influence the power factor in AC circuits?

Capacitors increase the power factor by reducing phase differences between voltage and current, often leading to a higher cosine of the phase angle.

What is the significance of series connection of capacitors in AC circuits?

In series configuration, the total capacitance is reduced, affecting the total voltage drop and increasing the reactance.

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