BasicB-005-010-002
How does a capacitor react to AC?
A
Answer
Transmitters, receivers, and measurements
Type
A
As the frequency of the applied AC increases, the reactance decreases
B
As the amplitude of the applied AC increases, the reactance increases
C
As the frequency of the applied AC increases, the reactance increases
D
As the amplitude of the applied AC increases, the reactance decreases
Answer Notes
A capacitor opposes changes in voltage. In an alternating current (AC) circuit, a higher frequency means the capacitor is charging and discharging more frequently, which effectively allows current to pass more easily.
This opposition to AC flow is called capacitive reactance. The formula is X_C = 1 / (2πfC). Because frequency (f) is in the denominator, the reactance is inversely proportional to frequency. Thus, as frequency increases, reactance decreases.
Just like with inductors, the amplitude of the applied AC has no effect on the reactance value itself.
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How does an inductor react to AC?
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The reactance of capacitors increases as: