Electrical Pressure or Force. Resistance is similar in many respects to mechanical friction. The resistance of a wire depends on its material, length, thickness and temperature. May be defined as the property of a circuit to oppose any change in voltage. May be defined as the property of a circuit to oppose any change in current.
Inductance can be in phase or out of phase.
As the current increases through an inductor, the magnetic field increases, exactly in step. At the instant the current reaches it's maximum positive value, it's rate of change is zero. This means maximum field strength but zero magnetic-field movement and therefore zero counter electro magnetic force due to moving magnetic fields. Thus maximum current and zero counter emf occur at the same instant with an alternating current applied. Without resonant circuits there would be no radio communication.