View your list of saved words. (You can log in using Facebook.)
Relationship between the potential difference (voltage), electric current, and resistance in an electric circuit. In 1827 Georg Simon Ohm discovered that at constant temperature, the current I in a circuit is directly proportional to the potential difference V, and inversely proportional to the resistance R, or I = V/R. Resistance is generally measured in ohms (). Ohm's law may also be expressed in terms of the electromotive forceE of an electric energy source, such as a battery, or E = IR. In an alternating-current circuit, when the combination of resistance and reactance, called impedance Z, is constant, Ohm's law is applicable and V/I = Z.
This entry comes from Encyclopædia Britannica Concise. For the full entry on Ohm's law, visit Britannica.com.