# Flow of electrons in a circuit

When the electrons flow in a circuit, so are those the electrons from the battery or are those the electrons of conductor like copper wire, etc..which are flowing in the circuit?

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Related question by OP: physics.stackexchange.com/q/53541/2451 –  Qmechanic Feb 11 '13 at 15:31

You can never tell them apart, so I think this question makes no sense. All electrons are identical, there's no such thing as electrons from the battery or electrons in the wire..

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When you first connect the battery the electrons flowing are mainly the electrons that were in the conduction band of the copper wire before you connected the battery. However the electrons obviously have to flow through the battery to complete the circuit. If we take the example of an alkaline battery, electrons flowing into the battery anode react with MnO$_2$ to produce Mn$_2$O$_3$ and hydroxide anions. At the cathode Zinc reacts with the hydroxide ions to produce zinc oxide and electrons, and these electrons flow into the wire.