Complex AC impedance calculator

Series RLC impedance magnitude at supplied frequency.

circuits-ac-impedance.napkin / editable

SCENARIO COMPARISON

Compare the numbers.

This source describes an analytical model. Its quantities and checks are the view.

Scenario	reactanceohm	magnitudeohm	currentA
	-96.3231	138.846	0.0720224
	-96.3231	125.212	0.0798643

All calculated quantities are listed with the inputs. Switch to Source to inspect the equations.

SCENARIOS / CALCULATED VALUESSAME SOURCE

Change an input to see the consequences.

current budget0.07 A✓ passes

BASELINE INPUTS

resistance100 ohminductance10 mHcapacitance1 uFfrequency1000 Hzvoltage10 V

CALCULATED

reactance-96.323 ohm

magnitude138.85 ohm

current0.072022 A

Edits change the baseline source.

THE SOURCE

Edits below update the same model.

# Complex AC impedance
# Scope: Series RLC impedance magnitude at supplied frequency.
# Status: illustrative worked example; engineering review pending.
# Inputs are example values. Checks are editable example requirements, not standards.

resistance = 100 ohm
inductance = 10 mH
capacitance = 1 uF
frequency = 1000 Hz
voltage = 10 V

reactance := 2*pi*frequency*inductance-1/(2*pi*frequency*capacitance) [ohm]
magnitude := sqrt(resistance^2+reactance^2) [ohm]
current := voltage/magnitude [A]

check current budget: current <= 0.1 A

scenario alternative: resistance = 80 ohm

Calculated from your source · not saved

Baseline · Baseline

current budget0.07 A ✓ passes

alternative · alternative

current budget0.08 A ✓ passes

Illustrative first-order example. Checks are editable requirements, not design standards. The broader topic may require additional equations, data, and validation.

Formula and units

This example uses the following equations. Input names and units match the editable source above.

reactance: reactance = 2*pi*frequency*inductance-1/(2*pi*frequency*capacitance) [ohm]
magnitude: magnitude = sqrt(resistance^2+reactance^2) [ohm]
current: current = voltage/magnitude [A]

Original worked example

These are the baseline values in the downloadable source. Edits above let you test your own values.

Given

resistance: 100 ohm
inductance: 10 mH
capacitance: 1 uF
frequency: 1000 Hz
voltage: 10 V

Calculated

reactance: -96.3231 ohm
magnitude: 138.846 ohm
current: 0.0720224 A

Assumptions and limits

Series RLC impedance magnitude at supplied frequency.

The requirement checks use the limits written in this example. Passing a check does not establish that the model covers every load, material behavior, or operating condition in a real design.

Download this .napkin example ↓

Take it further with your agent

Napkin keeps the inputs, equations, checks and assumptions together in one study. Your agent sets it up; you change the numbers.

Try with Claude ↗

codex 'Use Napkin (https://napkin.engineering/mcp, or the local Napkin plugin) to build a study: Complex AC impedance. Inputs: frequency; component values; topology. Outputs: impedance magnitude and phase. Model scope: Ideal or parameterized lumped components. Read napkin_capabilities and the current snapshot. Ask me for the values that matter, label assumptions with units, author .napkin source, validate it and apply it with napkin_source using the current revision, then open the study. Add checks for the limits I supply. Keep unsupported analyses explicit.'

Claude needs the Napkin connector; Codex needs the Napkin plugin. Set up your agent ↗

The broader study

The topic brief below describes the broader scope. The worked example above states the particular calculation it implements.

Inputs: frequency, component values, topology
Outputs: impedance magnitude and phase
Modes: calculate, compare, sweep
Drawing: Schematic and waveform

EXECUTABLE WORKED EXAMPLE · FIRST-ORDER MODEL · CHECK THE SCOPE & ASSUMPTIONS