Electrician Jobsite English & Troubleshooting
Ohm's Law Calculator
Enter any two positive values to calculate voltage, current, resistance, and power for an ideal DC resistive circuit. Free in-browser tool; not for installation sizing.
Page highlights
- Enter any two positive values and calculate the other two
- Supports all six V, A, Ω, and W input pairs
- Ideal DC resistive model only; not for wire or protective-device sizing
What this Ohm's law calculator solves
For an ideal DC resistive model, Ohm's law relates voltage, current and resistance as V = I × R. Electrical power is related as P = V × I. Enter any two positive values and the calculator derives the remaining two.
- Voltage and current: R = V ÷ I; P = V × I.
- Voltage and resistance: I = V ÷ R; P = V² ÷ R.
- Voltage and power: I = P ÷ V; R = V² ÷ P.
- Current and resistance: V = I × R; P = I² × R.
- Current and power: V = P ÷ I; R = P ÷ I².
- Resistance and power: I = √(P ÷ R); V = √(P × R).
Example: 12 V across 6 Ω
Enter voltage = 12 V and resistance = 6 Ω. The ideal calculation gives current = 2 A and power = 24 W. The result describes this mathematical model only; it does not select a real component or prove that a circuit is safe.
Scope and safety boundary
Use this page for positive-value paper exercises involving an ideal DC resistive load. It does not model AC phase angle, power factor, reactance, motor starting, voltage drop, temperature, conductor ampacity, installation method, fault current, protective-device behavior or local code.
Never use this calculator to choose wire size, breaker, fuse, equipment rating or authorize electrical work. Real measurements and energized work require suitable instruments, procedures, authorization and task-specific competence.
Formula sources and editorial status
The formula relationships were checked against US government references on 28 October 2026. This page has not received an independent professional review; the linked sources support the basic relationships, not a site-specific design decision.
AI study helper
Copy this page's public material to ask an AI tool for terminology explanations, bilingual comparisons or revision questions. Keep the sources and safety limits in its answer, then check against this page.
A study question to try
Using this material, explain three key terms in English and Chinese, then give me one comprehension question. Keep the original sources, jurisdiction limits and stop-work conditions. Say when the material does not answer something. Do not provide live electrical work instructions.
Copies public content only, without your answers, report drafts or learning progress. Nothing is sent automatically to an AI service. AI can make mistakes; it cannot verify site safety or authorize work.
Maintained by Elect Learn · Page updated： · First published：
No independent professional review is recorded. Cited sources do not imply review or endorsement by those organizations. Sources and review policy
Page Markdown · Page JSON · AI content index
This site provides learning materials and does not replace local rules, permits, site procedures, or qualified judgment.