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Specifically, I'm thinking of something like this, except where we're not assuming the current source and wire have zero resistance and hence zero voltage:

enter image description here

(To be clear, I know that intentionally creating a short circuit is generally a bad idea, because, at best, it can cause damage to circuit components if it's not immediately disconnected. I'm asking this question out of curiosity, not because I plan to build something with a short circuit.)

My question is, since any physical power source must have some nonzero resistance value, and so must the wire (at least, assuming we're not dealing with superconductors), there has to be a nonzero voltage in order for there to be a nonzero current, right? But how can there be a nonzero voltage if the circuit is grounded, since there's only the one node? That would seem to imply that there shouldn't actually be a current in such a circuit. But that surely can't be right, since otherwise short circuits wouldn't be something we need to be careful to avoid accidentally creating? So where am I going wrong in my reasoning here?

My instinct is to say that the circuit modal used in nodal analysis, where we always make some node the ground node, simply doesn't apply here. But if that's the case, then what model would apply?

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    \$\begingroup\$ Grounding is only relevant if current can flow to or from ground. In your diagram it can't as there's no return path. \$\endgroup\$
    – Finbarr
    Sep 6, 2023 at 23:38
  • \$\begingroup\$ If you can have infinitely low resistance, infinitely low voltage is required to create current. \$\endgroup\$
    – Drew
    Sep 7, 2023 at 2:21
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    \$\begingroup\$ If your wire has non-zero resistance, then draw that resistance in your circuit. You'll soon see that you do not only have a single node. \$\endgroup\$
    – brhans
    Sep 7, 2023 at 2:30
  • \$\begingroup\$ @brhans, ah this clears up my confusion, thanks. You should make it an answer and I'll accept it because it's completely correct. \$\endgroup\$ Sep 7, 2023 at 2:47

1 Answer 1

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My question is, since any physical power source must have some nonzero resistance value, and so must the wire (at least, assuming we're not dealing with superconductors), there has to be a nonzero voltage in order for there to be a nonzero current, right?

Correct; ohm's law applies.

But how can there be a nonzero voltage if the circuit is grounded, since there's only the one node?

The ground connection is irrelevant to what happens in and around the loop.

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