Electrical Circuit Calculators: Ohm’s Law, Series & Parallel

Interactive workspace initializes in your browser. Engineering method, assumptions, validation, and references are available below.

Engineering reference

Introductory Circuits: theory, method, and sources

This electrical engineering workspace publishes 10 governing equations, 5 stated assumptions, 3 documented boundaries, and 3 sources so the numbers it returns can be checked rather than taken on trust.

Calculations run locallyCalculation & source methodology

How this tool works

Fifteen guided modules connect basic electrical quantities to complete DC and introductory AC circuit behavior.

Each module states the engineering question, shows the governing relationship, calculates live results, and provides a schematic or unit-labeled graph.

Inputs, restored state, list lengths, graph samples, and numerical ranges are bounded before calculations and drawing.

Calculators and topics covered

circuits
ohms law
kirchhoff laws
resistors
capacitors
inductors
AC circuits
voltage
current
resistance
power
series circuit
parallel circuit
voltage divider

Core equations

V = IR

P = VI = I^{2} R = \frac{V^{2}}{R}

R_{\mathrm{series}} = \sum R

\frac{1}{R_{\mathrm{parallel}}} = \sum \left(\frac{1}{R}\right)

\sum I_{\mathrm{node}} = 0

\sum V_{\mathrm{loop}} = 0

V_{C} \left(t\right) = V_{f} + \left(V_{0} - V_{f}\right) e^{\frac{- t}{RC}}

I_{L} \left(t\right) = I_{f} + \left(I_{0} - I_{f}\right) e^{\frac{- tR}{L}}

Z = R + j \left(\omega L \frac{- 1}{\omega C}\right)

f_{0} = \frac{1}{2 \pi \sqrt{LC}}

Method and assumptions

Assumptions

Wires and ideal sources have zero internal impedance unless an equivalent resistance is explicitly provided.
Resistors are linear and temperature independent.
RC and RL modules use ideal first-order lumped components.
AC modules use sinusoidal steady-state RMS quantities and ideal components.
The resistor color-code module uses the standard four-band interpretation.

Limitations and design boundaries

This is an educational analysis tool, not a substitute for electrical safety procedures, component datasheets, SPICE simulation, laboratory measurement, or professional design review.
The workbench does not model parasitics, tolerance distributions, temperature rise, saturation, dielectric breakdown, source current limits, transmission-line effects, semiconductor nonlinearities, or electromagnetic interference.
High-voltage and high-current circuits can cause severe injury, fire, and equipment damage even when the arithmetic is correct.

Sources and references

Primary sources are preferred for ratings, standards, manufacturer data, and externally defined constants.

Source policy

Alexander and Sadiku, Fundamentals of Electric CircuitsIntroductory DC, transient, and sinusoidal circuit-analysis relationships.
Nilsson and Riedel, Electric CircuitsKirchhoff laws, equivalent circuits, first-order response, and AC analysis.
IEC 60062Reference convention for resistor color marking.

Focused calculator routes

Quick calculations from this workbench

These standalone calculators use calculation engines from this workbench and provide direct, focused pages for common engineering checks.

Browse all calculators →

Ohm’s Law Calculator

Solve for voltage, current, resistance, power, and conductance for an ideal resistive element.

Voltage Divider Calculator

Calculate unloaded and loaded divider output voltage, source current, load current, and loading error.