Physics & Technology

Ohm's Law Calculator: V=IR

Voltage, current, and resistance.

Foundation of electrical engineering.

Formula

V=I×R. Rearrange: I=V/R or R=V/I.

Power

P=VI=I²R=V²/R.

Examples

LED: 9V, 2V@20mA. R=(9-2)/0.02=350Ω
Household: 120V×15A=1800W max

Frequently Asked Questions

Ohm's Law?

V=IR. Voltage=current×resistance.

Calculate resistance?

R=V/I. 12V/2A=6Ω.

Low resistance?

Excessive current, overheating, short circuit.