Asked in FBISE Physics 2022 — Paper 2 2022Moderate

The capacitive reactance in a pure capacitive D.C circuit is:

Correct answer: D. Infinite

  • A. Very small
  • B. Very large
  • C. Zero
  • D. Infinite

Explanation

The capacitive reactance in a pure capacitive DC circuit is infinite. This is because a steady DC voltage causes the capacitor to charge up and then block any further current, acting like an open circuit. Therefore, no current flows through the circuit once the capacitor is fully charged. XC = 1/ωC As, ω = 2πf So, XC = 1/2πf.C In the case of DC, where the frequency ( ω = 2πf ) is zero, the capacitive reactance (XC) becomes infinite, as dividing by zero yields infinity.

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