How Capacitive Reactance Works?
Capacitive reactance (symbol XC) is the resistance offered by a capacitor to an AC (alternating current) signal. It works like resistance but it changes which depends on the frequency of the signal and the value of the capacitor.
The formula to calculate capacitive reactance is:
XC = 1 / (2 × π × f × C)
Where:
- XC is the reactance in ohms (Ω)
- f is the frequency in hertz (Hz)
- C is the capacitance in farads (F)
Key Points:
- Reactance is high at low frequencies and low at high frequencies.
- For DC (0 Hz) reactance is infinite—capacitor blocks it.
- For high-frequency AC, the capacitor easily allows current to pass.
Example:
- A 1 µF capacitor at 50 Hz has a reactance of about 3.2 kΩ.
- The same capacitor at 10 kHz will have a reactance of just 16 Ω.
This is why, capacitors are commonly used to filter out DC and pass AC especially in power supplies and signal processing.
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