Ohm's Law Calculator
Find voltage from current and resistance with Ohm's law — plus the power it dissipates.
Voltage20.00V
Power40.00W
Ohm's law is V = I × R: voltage equals current (amps) times resistance (ohms). At 2 A through 10 Ω the voltage is 2 × 10 = 20 V. Power follows from P = V × I = I² × R, so here P = 20 × 2 = 40 W. Rearrange Ohm's law to solve for any term: I = V ÷ R and R = V ÷ I.
Questions
What is Ohm's law?
Ohm's law states that voltage equals current times resistance: V = I × R. With 2 amps flowing through 10 ohms, the voltage across it is 2 × 10 = 20 volts.
How do I calculate power from Ohm's law?
Power is voltage times current, P = V × I, which also equals I² × R. For 20 V at 2 A the power is 20 × 2 = 40 watts.