Physics
Ohm's Law Calculator
Voltage, current, resistance
Calculate voltage, current, resistance, and power using Ohm's Law. Enter any two values to find the others.
Known Values
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How It Works
The Formula
V = I × R · P = V × I
V = volts · I = amps · R = ohms · P = watts
Worked Example
12V across 4Ω
- 1I = 12 ÷ 4 = 3 A
- 2P = 12 × 3 = 36 W
Result: 3 amps · 36 watts
Pro Tip
Check P = I²×R too — power dissipation heats components.
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