3 ms·
This example violates one of the core assumptions of circuit theory, which is that you cannot have a node with two voltages. As soon as the switch closes, is th
by vegetablepotpie 6y ago
This example violates one of the core assumptions of circuit theory, which is that you cannot have a node with two voltages. As soon as the switch closes, is the voltage at the switch Vi or 0v? It would be both, which is impossible. If you had some kind of component between the two then there would be a voltage drop across it, and you would get realistic results.
- aliceryhl 6y agoI mean, that is a simplification, and in the real world it really follows some sort of differential equation that just happens to be very fast. And the description on Wikipedia does seem to use an explanation based on this differential equation, e.g. see "When a steady state is reached".
- jackhalford 6y agoThe differential equation is still a model and not what's happening in "the real world", remember, all models are false.
- zoomablemind 6y agoThe system in question is not closed, as the state change requires application of external energy. Thus expecting a conservation of the initial energy only may be unwarranted. My intuition is that there's a missing counter-action energy which would be required in order to maintain the initial state in such a circuit. Once the state change is being effectuated (switch closed), it would change the balance of action-counter-action which would lead to dissipation in the real world. Not sure how to quantify/formalize it.
- wrycoder 6y agoIt’s insufficiently specified. There is actually a small resistance in series with an inductor between the nodes. There’s a time varying voltage across those. Edit: as a follow-on, the paradox is posed as a problem in electrostatics, when it’s actually a problem in electrodynamics.