Ohm's Law Calculator: Calculate V, I, R and Electric Power P
Calculate electrical voltage (V), current (amps), resistance (ohms), and power (watts) with Ohm's law circle formulas.
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How to Use the Ohm's Law Calculator: Voltage, Current, Resistance & Power
- 1Enter any two known values.
- 2The calculator determines the remaining two properties.
- 3View electrical power in watts and resistance in ohms.
Formula & How It Works
Ohm's Law & Joule's Law Wheel
Governs DC circuits. Source: NIST Electrical Metrology Standards.
Worked Examples
Calculating Resistor Current
Input: Voltage = 12V, Resistance = 4Ω
Explanation: I = 12/4 = 3A. P = 12 × 3 = 36W.
Frequently Asked Questions
What is Ohm's law formula?▼
V = I × R (Voltage = Current × Resistance).
Quick Reference & Conversion Table
| Property | Symbol | Unit | Unit Abbreviation |
|---|---|---|---|
| Voltage (Potential) | V | Volts | V |
| Current | I | Amperes | A |
| Resistance | R | Ohms | Ω |
| Power | P | Watts | W |
⚠️ Common Pitfalls to Avoid
- •Confusing AC impedance with simple DC resistance in inductive loads.
💡 Practical Real-World Uses
- •Sizing resistors for LED circuits.
- •Selecting electrical circuit breaker amperages.
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