Ohm's law applies to electrical circuits; it states that the current through a conductor between two points is directly proportional to the potential difference or voltage across the two points, and inversely proportional to the resistance between them. Or simply V I*R Note that Ohm's law apply only to ohmic materials i.e. Materials which obey ohm's law. Not all materials follow this V I*R relationship.
First of all, remember that the question only has meaning if you are discussing an AC circuit being driven by a sine wave (not a square wave or any other waveshape) In a resistor, the current flowing through it is in phase with the voltage applied across it. In a capacitor, the current flowing through it is π/2 Radians (or 90°) ahead of the voltage applied across it. (This is also called 'leading' the voltage) In an inductor, the current flowing through it is π/2 Radians (or 90°) behind the voltage applied across it. (This is also called 'lagging' the voltage) In a resistive circuit, it is the resistance value which limits the current flow. In an inductive or capacitive circuit, it is a thing called the 'reactance' of the capacitor (capacitive reactance) or the inductor (inductive reactance). Reactance is different from resistance in two very important ways. First, reactance is frequency dependent. That is, it changes as the frequency of the applied foltage changes. And it causes a π/2 Radian (or 90°) phase shift in the current flowing through the circuit. These are all very important things for you to know and know well. And I'm sure that your teacher will explain them during the class. Doug
