In the three tables to the right, you may enter two of the three factors in Ohm's (original) Law. They are Voltage (V) or (E), measured in Volts, Current or Amperage (I), measured in Amps (Amperes), and Resistance (R) measured in Ohms. The third factor will be calculated for you when you click on the Calculate button for that table.

Ohm's Law is V = I x R where V = Voltage, I = Current and R = Resistance. One ohm is the resistance value through which one volt will maintain a current of one ampere.

Georg Simon Ohm was the Bavarian physicist who determined the mathematical law of electric currents called Ohm's Law. The ohm, an electrical unit of resistance, was named for him. Between 1825 and 1827, he devised the theory or the relationships and it was credited to him in late 1827.

In later years, we have also attributed the Power factor to Ohm as well. Power is usually abbreviated by (W) and measured in Watts. For the Ohm's Law Calculations With Power, click here. To check the color codes of resistors, use our Resistor Color Code Table And Calculator. This converter requires the use of Javascript enabled and capable browsers.

Ohm's Law Factors (excluding Power)

Resistivity (W-cm) for Common Metals
at Room Temperature

Aluminum

2.828 x 10^{-6}

Copper

1.676 x 10^{-6}

Silver

1.586 x 10^{-6}

Gold

2.214 x 10^{-6}

Tungsten

5.510 x 10^{-6}

For example, a 10 Gauge wire is 2.588mm in diameter.
The resistance per cm of copper wire that thick is
3.186 x 10^{-5}W/cm.
A mile of this wire has a resistance of 5.13 W.