I can learn all the memorizable theory and equations there are, but I have always struggled to understand the actual physics behind conductivity.
Copper atoms have electrons on their outer-most shell that are free to move from one atom to another with little resistance (free electrons). Once one of these atoms becomes delocalized (i.e. pop's off), that Copper atom is now a positively charged ion called a "cation." These delocalized copper electrons are referred to as a "sea of delocalized electrons."
So... if you have a piece of copper wire that is 6 inches long, for example, and you connect it to a power source of any kind, and begin to run a current through that wire... the sea of delocalized electrons that begins to flow is made up of electrons—electrons are sub-atomic particles—sub-atomic particles have mass—as mass moves it physically changes from one place to another. Why does our 6-inch piece of wire not change at all? As this "sea of electrons" reaches the end of the wire, why do they not collect or bottleneck, or... in some way change the shape of the end of the wire?
I think maybe my mental picture is just false from the very beginning. If you connect the 6-inch piece of wire to the positive terminal of a 9V battery, no current is flowing. Correct? You could take a piece of copper wire, and connect it to JUST the positive terminal of a 600V power supply, and stick the other end in your mouth, and you will be completely fine. However, when you connect the copper wire to the negative terminal, that is when the current will flow, correct? In the case of 9V battery, the wire doesn't physically change, because it is simply acting like a bucket-brigade, taking electrons that are coming from the battery, passing those electrons along it chain of copper atoms that allow these electrons to pass through, and returning them to the other terminal of the battery, so that the chemical reaction in the battery can re-energize the electrons and send them around the loop again. i.e.... a circuit! So the wire ends up with the same number of copper electrons that it had before the current was sent through it.
I guess that answers my question huh? Copper wires do not physically change after a current has flowed through them, because current can only flow when a circuit is closed into a loop.
Copper atoms have electrons on their outer-most shell that are free to move from one atom to another with little resistance (free electrons). Once one of these atoms becomes delocalized (i.e. pop's off), that Copper atom is now a positively charged ion called a "cation." These delocalized copper electrons are referred to as a "sea of delocalized electrons."
So... if you have a piece of copper wire that is 6 inches long, for example, and you connect it to a power source of any kind, and begin to run a current through that wire... the sea of delocalized electrons that begins to flow is made up of electrons—electrons are sub-atomic particles—sub-atomic particles have mass—as mass moves it physically changes from one place to another. Why does our 6-inch piece of wire not change at all? As this "sea of electrons" reaches the end of the wire, why do they not collect or bottleneck, or... in some way change the shape of the end of the wire?
I think maybe my mental picture is just false from the very beginning. If you connect the 6-inch piece of wire to the positive terminal of a 9V battery, no current is flowing. Correct? You could take a piece of copper wire, and connect it to JUST the positive terminal of a 600V power supply, and stick the other end in your mouth, and you will be completely fine. However, when you connect the copper wire to the negative terminal, that is when the current will flow, correct? In the case of 9V battery, the wire doesn't physically change, because it is simply acting like a bucket-brigade, taking electrons that are coming from the battery, passing those electrons along it chain of copper atoms that allow these electrons to pass through, and returning them to the other terminal of the battery, so that the chemical reaction in the battery can re-energize the electrons and send them around the loop again. i.e.... a circuit! So the wire ends up with the same number of copper electrons that it had before the current was sent through it.
I guess that answers my question huh? Copper wires do not physically change after a current has flowed through them, because current can only flow when a circuit is closed into a loop.