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I am facing a problem with a voltage source with 0 current through it. Will the power of that source be 0 according to the formula P=V*i? Is there a reason to use such a source if it neither provides nor receives energy ? Thanks.

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    It's pretty useful for turning things off... – Ron Beyer Mar 17 '20 at 19:03
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    Are you talking about literally zero current? Or so little current it might as well be zero? Because literally zero current means it is an ideal voltage source with an infinite output resistance. So as soon as it tries to supply any non-zero level of current, all the voltage gets dropped across the output resistance and nothing is left on the output terminals. – DKNguyen Mar 17 '20 at 19:09

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... a voltage source with 0 current through it. Will the power of that source be 0 according to the formula P=V*i?

Yes, the power supplied from the source is zero if the current drawn is zero.

Is there a reason to use such a source if it neither provides nor receives energy?

Is there a reason to have a battery in my torch / flashlight if it's switched off? Yes, of course. It's there when it's needed.

I suspect that you have some idealised circuit in a homework problem and that the voltage source is in place to add a little confusion.

Transistor
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