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tomcat017
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Hello all - a quick question that I can't seem to find an answer to online that I trust...
While the conventional current model describes flow of positive charges around a circuit, we know that current is actually the flow of electrons (at least in common metallic conductors). Which leads to the question: which of these two resolutions regarding direction of current flow is correct (assume a simple circuit with one light bulb and a common AA alkaline battery).
1. The terminal of the battery labelled "+" is actually at a higher potential than the terminal labelled "-" (i.e. is accurately labelled). When the circuit is completed, electrons flow out of the negative terminal of the battery, lose potential energy as they transit the circuit, and return to the cell at the higher potential positive terminal. This means that the direction of current determined on circuit diagrams (from (+) terminal to (-) terminal) would actually be opposite the real direction of flow of electrons.
2. The terminal of the battery labelled "+" is actually at a lower potential (i.e. is really the negative terminal of the battery) than the terminal labelled "-" (which is really positively charged). When the circuit is completed, electrons flow out of the incorrectly-labelled (+) terminal, lose potential energy as they transit the circuit, and return to the cell at the (-) terminal. This means that while the labels on the battery wrapper are incorrect, the direction of current flow established in circuit diagrams is correct.
Both possibilities recognize and resolve the difference in direction between conventional and real currents, but they do so differently: one preserves the direction of current flow from diagram to real circuit (by mislabelling the battery), while one requires remembering that current flow is opposite.
I ask because someone once told me that in automotive circuit designs, charges actually flow from the positive to the negative terminal of the battery (from which, if that is accurate, I would infer that option #2 is correct). Wouldn't this difference matter in applications involving diodes? Or is that directionality issue also taken care of in the "labelling" of the diodes? Is this distinction completely inconsequential?
Forgive me if the question is an ignorant one - and thanks for the help,
While the conventional current model describes flow of positive charges around a circuit, we know that current is actually the flow of electrons (at least in common metallic conductors). Which leads to the question: which of these two resolutions regarding direction of current flow is correct (assume a simple circuit with one light bulb and a common AA alkaline battery).
1. The terminal of the battery labelled "+" is actually at a higher potential than the terminal labelled "-" (i.e. is accurately labelled). When the circuit is completed, electrons flow out of the negative terminal of the battery, lose potential energy as they transit the circuit, and return to the cell at the higher potential positive terminal. This means that the direction of current determined on circuit diagrams (from (+) terminal to (-) terminal) would actually be opposite the real direction of flow of electrons.
2. The terminal of the battery labelled "+" is actually at a lower potential (i.e. is really the negative terminal of the battery) than the terminal labelled "-" (which is really positively charged). When the circuit is completed, electrons flow out of the incorrectly-labelled (+) terminal, lose potential energy as they transit the circuit, and return to the cell at the (-) terminal. This means that while the labels on the battery wrapper are incorrect, the direction of current flow established in circuit diagrams is correct.
Both possibilities recognize and resolve the difference in direction between conventional and real currents, but they do so differently: one preserves the direction of current flow from diagram to real circuit (by mislabelling the battery), while one requires remembering that current flow is opposite.
I ask because someone once told me that in automotive circuit designs, charges actually flow from the positive to the negative terminal of the battery (from which, if that is accurate, I would infer that option #2 is correct). Wouldn't this difference matter in applications involving diodes? Or is that directionality issue also taken care of in the "labelling" of the diodes? Is this distinction completely inconsequential?
Forgive me if the question is an ignorant one - and thanks for the help,
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