Ohm's Law Calculator
Solve Ohm's Law (V = IR) for voltage, current, or resistance — enter any two values to find the third. Also calculates power (W) from the known values.
V
110 V
I
0.5 A
R
220 Ω
P
55 W
How to use the ohm's law calculator
Fill in any two of voltage (V), current (I), or resistance (R). The third and the power dissipation compute automatically.
Formula & explanation
V = IR. Power: P = VI = I²R = V²/R.
Examples
12 V across 220 Ω draws 54.5 mA, dissipating 0.65 W.
Frequently asked questions
- What is Ohm's law?
- Ohm's law states that voltage equals current times resistance (V = IR). It describes how the three fundamental electrical quantities relate in a resistive circuit.
- How do I find current if I know voltage and resistance?
- Divide voltage by resistance: I = V / R. For example, 9 V across a 180 Ω resistor draws 50 mA.
- Can I use this for AC circuits?
- Ohm's law applies directly to purely resistive AC loads. For reactive components (capacitors, inductors) you need impedance Z instead of resistance R.
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