Consider an RLC circuit,
and let $V_p$ be the amplitude of voltage from alternating current source,$$ V\left(t\right)~=~V_p \sin{\left(\omega t\right)} \,.$$In addition, let $V_{p,\,\text{resistor}}, V_{p,\,\text{coil}}, V_{p,\,\text{capacitor}}$ be amplitudes of voltage across the resistor, coil, and capacitor, respectively.

Then does$$ V_p = \sqrt{V_{p,\,\text{resistor}}^2+ {\left(V_{p,\,\text{coil}}-V_{p,\,\text{capacitor}} \right)}^2} $$ hold?

  • $\begingroup$ Is the $p$ ("peak"?) subscript information worth retaining in this context, or could it be dropped for brevity? $\endgroup$
    – Nat
    Commented May 31, 2018 at 22:19
  • $\begingroup$ Nat, the "p" is to make it absolutely clear that the voltages are Peak and not RMS, which is most common in electrical engineering $\endgroup$
    – Albert
    Commented Jun 1, 2018 at 11:12

1 Answer 1


If the RLC circuit has R, L, and C connected in series and V(t) is the voltage across the complete series, the answer is yes:


  • $\begingroup$ You accidentally squared the left hand side :) $\endgroup$ Commented May 31, 2018 at 22:15

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