Mechanics Practice Exam 2025 – Complete Study Guide for Success

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What is the effect of increasing frequency on the impedance of a capacitor?

Impedance increases

Impedance decreases

In the context of a capacitor in an AC circuit, impedance is defined as the opposition that the capacitor presents to the flow of alternating current. The impedance of a capacitor (Z) is given by the formula:

\[ Z = \frac{1}{j\omega C} \]

where \( j \) is the imaginary unit, \( \omega \) is the angular frequency (related to frequency by \( \omega = 2\pi f \)), and \( C \) is the capacitance.

From this formula, we can observe that the impedance of a capacitor is inversely proportional to the frequency. As the frequency increases, the angular frequency (\( \omega \)) also increases, leading to a decrease in the magnitude of the impedance. This means that at higher frequencies, the capacitor allows more current to flow through it, reducing its overall opposition to current flow.

Therefore, as the frequency increases, the impedance of a capacitor decreases, confirming that increasing frequency results in lower impedance.

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Impedance remains constant

Peak current becomes null

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