Keep it simple please, I am just a 10th grader aspiring to become like you guys and solve complex equations but as of now I came across the chapter current and it said that current is opposite to the flow of electrons and the charge of current is unknown but if all the electrons are flowing in one direction, the current has to be of position charge meaning current is the flow of cations? Am i right? If not please tell amd also tell what is this current made of ? Protons? Cations? Anions? Electrons? Something not yet discovered? What?
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$\begingroup$ have a look here hyperphysics.phy-astr.gsu.edu/hbase/electric/miccur.html $\endgroup$– anna vCommented Sep 20, 2023 at 5:12
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5 Answers
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Current is the collective movement of charge across a surface per unit time. The charge that is mobile (free to move between atoms) in metal conductors is the negative charge of electrons. The positive charge of protons are generally not free to move.
A long time ago before the nature of current was fully understood, current was thought to be the flow of positive charge, a convention that remains with us today in electrical engineering (to the chagrin of physicists!).
But motion is relative. If I’m sitting on a moving electron it is the protons that appear to move. If I’m on a proton, it is the electrons that appear to move. For basic circuit analysis it doesn’t matter.
Hope this helps.
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3$\begingroup$ The ion currents in the neurons you used to compose this answer are predominantly a flow of positive ions. The current in a common Li ion battery is positive ions. $\endgroup$ Commented Sep 19, 2023 at 18:43
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$\begingroup$ @JohnDoty I wanted to keep it simple $\endgroup$– Bob DCommented Sep 19, 2023 at 18:52
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$\begingroup$ But Positive charge doesn't move I thought $\endgroup$– user378151Commented Sep 20, 2023 at 9:57
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2$\begingroup$ @memeguy it can move in ionized gases and liquids where the atoms themselves are free to move. $\endgroup$– Bob DCommented Sep 20, 2023 at 10:50
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Current is the flow of charge. That virtually always means the flow of some charge carrying particle.
In static electricity cases, you don't need to have electrons flowing one way and something else flowing another, because you start with one object charged with extra electrons, and they simply flow in one direction (until the charges equalize, and then the current stops). In the case of non-static electricity, electrons typically flow in a loop, given energy from a power source like a battery. Thus, in that case, we again do not see the need for a counter-current of charge... everything just flows in a loop.
answered Sep 19, 2023 at 19:20
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If not please tell amd also tell what is this current made of ? Protons? Cations? Anions? Electrons? Something not yet discovered? What?
For now, you can think of the relevant charged particles that are flowing to be the electrons. For real materials like metals, these electrons are often called "conduction electrons." The "conduction electrons" are not all the electrons, but are the relatively weakly bound atomic electrons that are relatively free to roam about the solid.
The electrons, by convention, have negative charge.
The direction of current flow is, by convention, in the direction of flow of positive charge.
Therefore, even if there are no positively charged particles flowing (as I have asked you to assume), there can still be a positive flow of current. The positive flow of current is in the opposite direction as the flow of electrons.
Caveats:
In some materials a positively charged quasi-particle called a "hole" can be considered the current carrier. In these materials the current is the sum of the (positive) current due to holes minus the (negative) current due to electrons.
In some systems, e.g., plasmas, the current is due to both positively charged ions (cations) as well as negatively charged electrons.
Generally, there are lots of different type of systems and lots of different types of electric charge carriers (as you mentioned, anions, cations, electrons). Free protons are not usually relevant in the case of conduction in solids at earth-based temperatures and pressure, but could be relevant in hot plasmas, in which case they could also be described as "cations" (since a hydrogen atom without its electron is a proton).
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In general, the electric current is the flow of net electric charge per unit of time through a normal plane under consideration.
Conventionally, the direction of electric current is taken along the flow of positive charge such as protons, and cations, while the direction of current is conventionally taken opposite to the flow of negative charge such as electrons and anions.
answered Sep 19, 2023 at 17:55
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In simple terms, you can understand it as, when anything with charge moves, it creates something known as "current". so, its just the flow of charges, be it electrons(-ve charges) or protons(+ve charges) or anything else. So current is made of charges.
This is something, which we understand now, but a long long time ago, physicists assumed that current was only the flow of positive charges, and so when electrons(-ve charged) moved or flowed, it was assumed that current, being opposite to the flow of -ve charge, would be in the opposite direction as well. So, it's simply a convention to think of current flow to be opposite to that of electrons flow. And as movements and motion in general is relative, it doesn't make an impact. And that's maybe why, till this day, we follow that convention. Hope this helps! Be curious!
