What Is DC and AC Resistance?

Resistance in AC and DC currents is the ability of a material, normally a circuit or a resistor, to oppose or restrict the flow of current through it. The amount of resistance that a material gives is referred to as an ohm. Several common materials with high resistance levels include wood, tungsten, air, glass and rubber.

The longer a wire or the material being used to conduct the electricity the higher the resistance will be. In AC current, when it passes through material, it creates a magnetic field across the material. This opposes the flow of current in addition to the natural resistance that might be produced by the material it is passing through. This is referred to as inductance, but is an action or state that only occurs in the AC currents. A DC current has a lower resistance than an AC current because the only factor that resists in a DC set up is the wire or material that the current is passing through. There is no inductance associated with DC currents due to there being no frequency in this type of current. This basically means that the DC current is constant. When resistance is being factored there is a temperature dependence, but as long as the temperature is known then the resistance can still be measured.