Ohm's Law Calculator
Ohm's Law defines the relationship between electrical potential (Voltage), charge flow rate (Current), and electrical resistance. Combined with Joule's power law (P = VI), these equations form the foundation of electrical and electronic circuit analysis.
Select the two electrical quantities you already know
Electric potential difference across the circuit in Volts
Electric current flow in Amperes
Electrical resistance in Ohms (Ω)
Electric power dissipation in Watts
Total electrical power consumed or dissipated in Watts
How to Use This Calculator
- Select which two electrical quantities you already know from the dropdown.
- Enter their numerical values into the corresponding input fields.
- Review the computed values for power, voltage, current, and resistance.
Formula & Calculation Methodology
Ohm's Law states that voltage is the product of current and resistance. Joule's Law relates electric power directly to voltage and current.
Worked Example
120V Line with 10A Draw
50 Ohm Resistor with 2A Current
Frequently Asked Questions
Does Ohm's Law apply to AC circuits?↓
Yes, for purely resistive loads. In circuits with inductors or capacitors, resistance R is replaced by AC impedance Z.
What is the relationship between Watts and Volts?↓
Watts measure total power (rate of energy transfer), while Volts measure potential difference. At 1 Amp, 1 Volt delivers 1 Watt.
What causes a dead short circuit?↓
A short circuit occurs when resistance drops near zero, causing current to spike uncontrollably until limited by a circuit breaker.
Are semiconductors ohmic devices?↓
No, semiconductor diodes and transistors exhibit non-linear voltage-current curves and do not follow linear Ohm's Law.
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Source Citation & Disclaimer
Informational tool only; not licensed tax, legal, or financial advice.