Resistance is that the opposition that a substance offers to the flow of electrical current. it's represent by the uppercase letter R. the quality unit of resistance is that the ohm, typically written out as a word, and typically symbolized by the uppercase Greek letter omega: Greek letter omega.

Resistance will be delineated in terms of its bulk resistivity. The resistivity and so the resistance, is temperature dependent. Over sizable ranges of temperature, this temperature dependence will be foretold from a temperature coefficient of resistance.

The electric resistance of Associate in Nursing object could be a live of its opposition to the flow of electrical current. The inverse amount is electrical current, and is that the ease with that an electrical current passes. electric resistance shares some abstract parallels with the notion of mechanical friction.

In general, once the applied voltage is control constant, this during a direct-current (DC) circuit is reciprocally proportional to the resistance. If the resistance is doubled, this is cut in half; if the resistance is halved, this is doubled. This rule additionally holds true for many low-frequency alternating-current (AC) systems, like house utility circuits. In some AC circuits, particularly at high frequencies, true is additional advanced as a result of some elements in these systems will store and unleash energy, similarly as dissipating or changing it.