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Ohm's Law

A mathematical equation that shows the relationship between electric voltage, current and resistance. Ohm��s Law was named after Bavarian mathematician and physicist Georg Ohm.

Ohm��s Law can be stated as three mathematical equations, all derived from the same principle. In the following equations, V is voltage measured in volts, I is current measured in amperes and R is resistance measured in ohms:

  • V = I x R
  • R = V / I
  • I = V / R
Knowing any two of the values of a circuit, one can determine the third using Ohm��s Law. For example, if a circuit has a current of 2 amperes, and a resistance of 1 ohm, then according to Ohms Law, voltage equals 2 (V = 2 x 1).

Typically, Ohm��s Law is only applied to DC circuits and not AC circuits.

Note well: The letter "E" is sometimes used in representations of Ohm��s Law for voltage instead of "V."

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