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What happens to a capacitor's reactance as frequency rises?

It falls, since X_C = 1 / (2 pi f C).

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  1. It rises
  2. It falls ✔
  3. It stays the same

Why: Capacitive reactance is 1 divided by 2 pi f C, so it drops as frequency goes up. At higher frequency there is less time to fully charge the capacitor.

Huh, didn't know that: Doubling the frequency cuts a capacitor's reactance in half.

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References

Answer: It falls. Capacitive reactance is 1 divided by 2 pi f C, so it drops as frequency goes up. At higher frequency there is less time to fully charge the capacitor.

  1. Physics LibreTexts (OpenStax College Physics), 23.2 Reactance, Inductive and Capacitive phys.libretexts.org/Bookshelves/College_Physics/College_Physics_1e_(OpenStax)/23:_Electromagnetic_Induction_AC_Circuits_and_Electrical_Technologies/23.02:_Reactance_Inductive_and_Capacitive
    the greater the frequency, the less time there is to fully charge the capacitor
    Checked 2026-10-11.

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