Ohm's Law

Ohm's Law


In the three tables below, 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. To check the color codes of resistors, use our Resistor Color Code Table And Calculator.

Ohm's Law Factors (excluding Power)

To calculate the circuit voltage... The formula is V = I x R Input the Current Amps Input the Resistance Ohms       Calculated Voltage Volts

To calculate the circuit amperage... The formula is I = V / R Input the Voltage Volts Input the Resistance Ohms       Calculated Current Amps

To calculate the circuit resistance... The formula is R = V / A Input the Voltage Volts Input the Current Amps       Calculated Resistance Ohms

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^-5W/cm. A mile of this wire has a resistance of 5.13 W.