Welcome Back

Sign in to your PART66Online account

or use email
Forgot password?

Don't have an account? Register here

Module 3. Electrical fundamentals

A circuit containing a resistor, capacitor and inductor where resonant frequency is met, what will the impedance of the circuit be?

  • Maximum.
  • Resistance across the resistor.
  • Zero.

Explanation

At resonance the equal inductive and capacitive reactances cancel, so they contribute nothing to the opposition. The impedance of the series circuit therefore equals just the resistance of the resistor, which is its minimum value, not maximum or zero.

Wesley asking:

The question does not say if the LCR circuit is in series or parallel.
Series RLC at resonance: XL and XC cancel, leaving only R. Impedance = low (just R, could be very low if R is small).
Parallel RLC at resonance: XL and XC still cancel in terms of reactance, but because the components are in parallel, this results in high impedance — approaching infinite in the ideal case

Community Comments (1)

M
Marek_AME Posts: 4 01.07.2026 / 12:51
B. You are right, question does not say series or parallel, marked answer fits the series case where XL and XC cancel and only resistor remains, in parallel it would be maximum instead.

Please Sign In to post a comment.

We use essential cookies to keep you signed in, plus anonymous analytics to understand how the site is used. Cookie-based analytics is set only with your consent. See our Privacy & Cookie Policy.