# Capacitor vs Inductor - who wins?

The idea behind the question is to determine which one of the two - capacitor or inductor will drive the current in the circuit when connected in a specific way.

Say I have a circuit in which I have saturated inductor and then I connect a charged capacitor to this saturated inductor. (Here, saturated inductor means a circuit which possesses the maximum energy it can hold in its magnetic field.)

Now, the inductor would have had the current moving in some particular direction through it for it to get saturated ( say A to B).And the capacitor would also have its positive and negative plates as per how it was charged (let C be the positive plate and D the negative plate.)

Now,will the current flow through the circuit (after the key is opened as the function of that circuit was to saturate the inductor) due to the inductor - keeping with the inductor's characteristic to keep the direction of current through it constant. If this is true, then the inductor will charge an already charged capacitor?

Or, will the capacitor discharge and charge the already saturated inductor?

The main doubts here are:

1. What decides the priority? That is, what is the factor that decides if the capacitor or the inductor will 'win' and be the one deciding the current flow.

2.Also, is this dependent on the capacitance or inductance values? That is, is there some value of capacitance or inductance that will override the priority(?).

• Can I assume (1) the inductor and capacitor are "ideal", (2) there is initially a switch between A and C (or between B and D) that was open for a long time and (3) your question pertains to the instant the switch closes? Oct 8, 2022 at 13:54
• Oh yeah.. No problem with that. I connected the capacitor directly because I wanted no wastage of energy in either field through any means. Also, the capacitor and inductor are ideal. Oct 8, 2022 at 14:12

## 1 Answer

If the current from the inductor is going into the positive terminal of the capacitor then the capacitor will act to reduce the current in the inductor but the inductor will act to increase the charge on the capacitor. Since the capacitor is at its limit it will fail as it is pushed further. The inductor will not fail as it is backed away from its limit.

If the current from the inductor is going into the negative terminal of the capacitor then the capacitor will act to increase the current in the inductor but the inductor will act to decrease the charge on the capacitor. Since the inductor is at its limit it will fail as it is pushed further. The capacitor will not fail as it is backed away from its limit.

• Can you give me the summary in a "this will get priority in this situation" way? Oct 8, 2022 at 14:13
• @MockingYak978 do you really need a summary of two short paragraphs? Current into +, capacitor fails. Current into -, inductor fails. There isn't really "priority". Just one way one component fails and the other way the other fails.
– Dale
Oct 8, 2022 at 14:44