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Studying the fundamentals of circuit theory, I was reading the Wikipedia article on the Passive Sign Convention and found out about the Active Sign Convention (ASC). After searching many introductory circuit theory books - such as Nilsson's and Dorf's ones -,I realized that almost none of them mentions "Active Sign Convention". When some circuit element is with the current entering in the negative terminal, they say something like "the current and voltage reference directions are not in conform to the passive sign convention", as shown in the pictures below:

Do not adhere to the passive convention Images sources: Introduction to Electric Circuits, 9th Edition - James A. Svoboda, Richard C. Dorf

Searching more about the ASC, I have found these lecture notes that states (page 6):

Also, what's with the "Not Passive Sign Convention"? In general, circuit elements that absorb power (like resistors) are called passive elements, and circuit elements that supply power (to the circuit!) are called active elements. But for some reason, the opposite of the passive sign convention is not called the active sign convention. (Of course, people use the term active sign convention, but they are not supposed to. If you want to be an alpha geek, find out why and go around correcting them!) Instead, the awkward term "Not passive sign convention" is used. Actually, the full blown correct expression is "The element does not conform to the passive sign convention." But that's way too long to say or write (unless you are being the alpha geek).


So, my question is: Why "the opposite of the passive sign convention is not called the active sign convention"? Why they use "the current and voltage reference directions are not in passive sign convention" instead of "the current and voltage reference directions are in the active sign convention"?

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    \$\begingroup\$ Sometimes, people name something so they can communicate more efficiently, once the parties each share the name and its meaning (without having to explain it all over again.) Sometimes, it's better NOT to then create two names for the two different permutations. If might be even more efficient for communication once both are shared, but then you have to establish twice the sharing in the first place. So it might be sometimes better to find a middle balance. But you are asking to get into the minds of those who write such stuff. I'd have avoided the naming entirely. So I can't help you there. \$\endgroup\$ – jonk Mar 19 at 22:10
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    \$\begingroup\$ My opinion, having taught circuit theory for a few years, is that there is no benefit in talking about an "active sign convention". And you misstated a bit; it is not an element that does not follow the PSC, it is the directions of current and voltage that may not satisfy the PSC. Every text I used teaches that if the current and voltage follow the PSC then P=VI, otherwise P= -VI. Positive power is power absorbed, negative power is power provided. Also, Ohm's Law needs a negation if PSC is not followed. \$\endgroup\$ – Elliot Alderson Mar 19 at 22:34
  • \$\begingroup\$ @ElliotAlderson "it is not an element that does not follow the PSC, it is the directions of current and voltage that may not satisfy the PSC". I fixed it now, thanks. \$\endgroup\$ – Vinicius ACP Mar 19 at 23:25
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    \$\begingroup\$ @ViniciusACP I can't help you with, "*why the author of the lecture" appears to speak out of both sides of the mouth at once. You'd have to ask them. I can't read their mind for you. Like I said, I wouldn't even use either phrasing even when communicating to others unless there was a really good reason. I think you may be worrying too much about this. But perhaps that's because someone is forcing you to worry about it. Just avoid them, I'd say, if so. This is too much ado over some foolish conundrum that means nothing in the end. (In my opinion.) \$\endgroup\$ – jonk Mar 20 at 0:18
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    \$\begingroup\$ There's no need to introduce a term that won't ever be used in the book again. They're trying to teach what passive sign convention is, not what the opposite thing is. My book doesn't even mention the opposite. It's confusing enough for beginners to handle just the one. \$\endgroup\$ – DKNguyen Mar 20 at 3:54

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