What is electrical impedance?
Impedance is the name given to the all the elements in an electrical circuit which resist current flow and is measured in ohms. When the applied voltage is D.C. i.e from a battery this consists of pure resistance R. However when the applied voltage is A.C the voltage has a frequency f and this produces two other sources of impedance, which are called reactance. There are two types of reactance, inductive and capacitive. Inductive reactance XL is produced e.g. by coils and capacitive reactance XC is produced e.g by capacitors. Inductance is given the symbol L and Capacitance is given the symbol C. Inductive reactance XL is given by the expression 2 x pi x f x L. Inductive capacitance XC is given by the expression 1/(2 x pi x f x C). To understand how to manipulate R, XL, and XC to give total impedance in any A.C circuit requires knowledge of A.C. circuit theory and I recommend you follow this up.
