This is as a result of reactance, either capacitive, inductive or both and when talking about Ac circuits you have an impedance Z which is the sum of all reactances and resistance. In a Dc circuit all the numbers will be real, once you move into Ac you get both real and imaginary numbers where J notation is used to indicate the imaginary part. The terms you often encounter will be real power and reactive power, reactive power is real but delivers no energy to the load so think of it as wasted energy at twice the frequency and only the real power delivers. The big thing to remember about reactances like capacitance and inductance are they can be thought of as frequency dependant resistances that give either a + or - 90° phase shift in pure form. The way to remember the direction of phase shift is CIVIL Capacitance C where current I leads voltage and Inductance L where current I lags voltage.
Electrical theory can be real fun, these reactances and resistances can be in series / parallel and many different combinations and can make circuit analysis really interesting, a great way to exercise the grey mater and once you have exhausted Ac circuits, Kirchoffs laws, Superposition theorems and loop analysis you can move on to introducing magnetic's and take the good old radian into the 3D domain with three dimensional geometry and the sterradian !! To go further leaves electrical engineering behind and we get into electronics where we work in both the time and frequency domains but that is another story.
By the way all this is unknown to the domestic installer and is knowledge known to real electrical engineers or have been bothered to learn the subject.
Electrical theory can be real fun, these reactances and resistances can be in series / parallel and many different combinations and can make circuit analysis really interesting, a great way to exercise the grey mater and once you have exhausted Ac circuits, Kirchoffs laws, Superposition theorems and loop analysis you can move on to introducing magnetic's and take the good old radian into the 3D domain with three dimensional geometry and the sterradian !! To go further leaves electrical engineering behind and we get into electronics where we work in both the time and frequency domains but that is another story.
By the way all this is unknown to the domestic installer and is knowledge known to real electrical engineers or have been bothered to learn the subject.
