RLC Voltage Drop Calculator for Series AC Circuits

Calculator inputs

Source Voltage (V RMS)

Enter the applied AC supply voltage.

Resistance R (Ω)

Use total series resistance here.

Inductance L (mH)

Enter inductance in millihenry.

Capacitance C (µF)

Enter capacitance in microfarad.

Operating Frequency (Hz)

Use the present supply frequency.

Decimal Places

Choose output precision.

Sweep Start Factor

Graph starts at frequency × factor.

Sweep End Factor

Graph ends at frequency × factor.

Sweep Points

Higher points produce smoother curves.

Example data table

Source Voltage	R	L	C	Frequency	Impedance	Current	VR	VL	VC	Phase Angle
120 V	15 Ω	60 mH	220 µF	50 Hz	15.6267 Ω	7.6792 A	115.1878 V	144.7492 V	111.1073 V	16.2811°

This example shows how resistive and reactive drops shift with the same series current.

Formula used

X_L = 2πfL

X_C = 1 / (2πfC)

X = X_L - X_C

Z = √(R² + X²)

I = V / Z

V_R = I × R

V_L = I × X_L

V_C = I × X_C

φ = tan^-1((X_L - X_C) / R)

f_r = 1 / (2π√LC)

These equations model a series RLC circuit under sinusoidal steady-state conditions.

The source voltage equals the phasor sum of the resistive drop and net reactive drop.

How to use this calculator

Enter source voltage in RMS volts.
Enter series resistance in ohms.
Enter inductance in millihenry and capacitance in microfarad.
Set the operating frequency in hertz.
Choose decimal places for output formatting.
Define graph sweep factors and total sweep points.
Press the calculate button.
Review voltage drops, phase angle, impedance, power, and resonance values.
Use CSV or PDF export for reporting.
Compare the graph to study frequency-driven voltage changes.

Frequently asked questions

1. What does this calculator compute?

It computes series RLC impedance, current, voltage drops across resistor, inductor, and capacitor, plus phase angle, power factor, power values, and resonant frequency.

2. Why can inductor or capacitor voltage exceed source voltage?

In a series RLC circuit, reactive voltages oppose each other vectorially. Their individual magnitudes can rise above source voltage while the phasor combination still matches supply voltage.

3. Is this for series or parallel circuits?

This page is built for series RLC analysis. In parallel circuits, each branch sees the same applied voltage, so branch current calculations become the main focus.

4. Which voltage value should I enter?

Enter RMS source voltage for standard AC engineering work. If you only know peak voltage, convert it to RMS before using the calculator.

5. What happens at resonance?

At resonance, inductive and capacitive reactance are equal. Net reactance becomes zero, impedance approaches resistance, current peaks, and component voltage magnification may increase.

6. Why does the graph use sweep factors?

Sweep factors create a frequency range around your operating point. This helps you inspect how each component voltage changes above and below the selected frequency.

7. Can I use millihenry and microfarad directly?

Yes. The form accepts millihenry and microfarad. The code converts them internally into henry and farad before running the equations.

8. What does the vector source check mean?

It verifies that calculated component drops combine correctly in phasor form. A close match to source voltage confirms the result is internally consistent.