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 Reactance and Impedance Inductive

 I was tempted to call this subject "the three Rs of electrical theory", because it's one of the most standard subjects that every student probably learns in their first EE class; However, as you may have noticed, "Impedance" doesn't start with a letter R, so I couldn't do that. :( Nonetheless, these three forces, which are closely linked, are indeed important to the beginning electricity/electronics student. The good news is that they are relatively simple to understand, and can be dealt with using a few fairly easy and standard math formulas. Resistance is a force that tends to resist the flow of electrical current. Resistance is usually created deliberately by a resistor, a device used to create resistance in a circuit. Resistance is pretty straightforward: The more resistive a resistor is (i.e. the more ohms it's rated for), the more it restricts the flow of electricity through it. Perhaps the best news of all is that you only need to concern yourself with resistance if you're working with DC (direct current); The slightly more complicated concepts of reactance and impedance only exist in the world of AC (alternating current). Reactance, unlike resistance, is usually undesirable in a circuit. Whereas resistance is created by a resistor to achieve some effect, reactance is an unfortunate by-product of certain electrical components. There are two basic types of reactance: Capacitive reactance and inductive reactance. Appropriately enough, capacitive reactance is created by capacitors, while inductive reactance is created by inductors. Using either of these device types in an AC circuit will introduce some reactance. Like resistance, reactance is expressed in ohms, and it behaves in much the same way as resistance, in the sense that it tends to restrict the flow of current through a circuit.