Since there is no resistance in an LC circuit (not attached to an AC source), what's stopping the current from rising to infinite. And if resistance is provided by the inductor by self induction, then why does the current become infinite when an AC source is added to an LC circuit at resonant frequency? what am i missing?
LC Oscillations – What is the Amplitude of Current in LC Oscillations?
capacitanceelectric-circuitselectric-currentelectromagnetisminductance
Best Answer
Assuming no driving voltage, typically the capacitor starts with some finite amount of charge, or a finite amount of current is in the circuit. This is analogous to a mass-spring system that starts at a finite displacement or a finite initial velocity.
An ideal inductor does not provide resistance. It provides reactance, which is a "resistance" to a change in current. The main difference to point out here is that resistance dissipates energy while reactance does not. This is analogous to the mass-spring system where inertia "resists" a change in velocity.
Because the AC power source is providing more and more energy without any of it being dissipated.