............................................................................REACTANCE............................................................................................
Reactance is similar to resistance in that it is a measure of how much a component opposes the flow of current, however with reactance we are talking about alternating current only.
There are two types of reactance .......capacitive........and........ inductive, both oppose the flow of AC but have different properties
In an inductor ( coil of wire ) the current takes time to build up after the voltage is applied to it and so is said to lag the voltage by a certain time
In a capacitor a large current will have to flow to charge it up before the voltage can build up across its plates and so here the voltage lags the current in time
In a resistor the current exactly follows the voltage applied to it, it has no lag or lead in time
On their own however they both have the same effect as a resistor in as much as they all oppose the flow of current,.. its when we combine them in a cct that things become a bit more complex ( see the resonance page )
Also the two reactances behave differently when Alternating current is applied across them
A capacitor has its maximum reactance ( AC resistance ) at low frequencies, this drops in proportion to the applied frequency ie at a very low frequency it would behave as a very high value resistor, but at a high frequency it will behave as a short circuit
An inductor behaves as the exact opposite to the capacitor ie at high frequencies it has a very large reactance and at very low frequencies it behaves as a short circuit