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In my high school, the definition of electrical current is "the flow of charges" but I have seen a video about how electricity actually works and it seems to me that electrical current is indeed caused by the electric fields along the conductor and there is nothing to do with the flow of electrons (or charged particles). https://youtu.be/oI_X2cMHNe0?feature=shared

Could you please tell me if the definition of electricty when I am in high school is true or not ?

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    $\begingroup$ Well, voltage causes the fields that make electrons move that is current… $\endgroup$
    – Jon Custer
    Mar 7 at 22:03
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    $\begingroup$ What time in the video are you asking about. He probably says that electric power is carried by the fields outside the wires, and not by the current in the wire, which is a valid point of view. But where does he say that current is a field effect and not the motion of charged particles? (But also you can google the term displacement current for an effect that has similar consequences to current, such as producing magnetic fields, but doesn't involve moving charge) $\endgroup$
    – The Photon
    Mar 7 at 23:22
  • $\begingroup$ For A/C power, the electrons don't "flow". They experience a high frequency (e.g., 50 or 60 Hz), low amplitude back-and-forth "wiggle" around fixed positions. $\endgroup$ Mar 8 at 18:51

6 Answers 6

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electrical current is "the flow of charges"

The above is true.

it seems to me that electrical current is indeed caused by the electric fields along the conductor

The above is true as well.

there is nothing to do with the flow of electrons (or charged particles)

This is false.

Electric current is the flow of charges. It is measured in Amperes, which are Coulombs per second. Coulombs are a measure of charge. The current in Amperes through a cross section of wire is the net amount of charge that passes through the cross section per second. Net charge passing through a cross section implies motion of charge.

But, what causes charge to move in a uniform direction? When a battery slightly shifts the distribution of electrons in the wire, an electric field is created. This causes the motion of the electrons to be in a particular direction on average.

So, the electric field "pushes" the electrons and causes current.

Many introductory classes do not cover the specifics of electric field in wires and how electrons flow which is why there are a lot of misconceptions about it. The video you linked does a very good job of explaining it with visuals, so it may be worth watching again.

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    $\begingroup$ @GiorgioP-DoomsdayClockIsAt-90 But if I'm correct there's not transport of energy either in those rings. So no power flows. $\endgroup$
    – HarryH
    Mar 8 at 17:24
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    $\begingroup$ You are right. But it is a case that must be considered to answer the original question. There is a current, a flow of electric charges, but without an electric field. $\endgroup$ Mar 8 at 18:35
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    $\begingroup$ @InTheSearchForKnowledge The water-pipe analogy might help here: When you open a water tap in your house, individual water molecules take a long time to get from the well or the water tower or whatever to the faucet, but water (normally) will still start flowing immediately, because the pipes are already full of water and it all starts moving "at once" (see footnote in next comment). In the same way, the wires are already full of mobile charge carriers, and when you close the switch they all start moving "at once" (footnote). $\endgroup$
    – zwol
    Mar 8 at 20:40
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    $\begingroup$ @InTheSearchForKnowledge Footnote: "At once" really means "at the speed at which a pressure wave propagates in the medium"; for water, that's the speed of sound in water (roughly 1500 meters per second). For wires, this is where the electric field comes into play; a pressure wave of electrons in a conductor is (as far as I know) the same thing as an electromagnetic wave in/near the conductor, and it'll move at something like two-thirds of the vacuum speed of light. In both cases this is too fast to perceive without specialized instruments. $\endgroup$
    – zwol
    Mar 8 at 20:44
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    $\begingroup$ @zwol (and InSearchForKnowledge): note that electric-field propagation isn't limited to just linearly along the wire. Flipping a switch can cause current to start flowing in a light bulb that's physically near the switch but electrically very far away, with long wires that go many kilometers out and back. Veritaseum made a video about this (youtube.com/watch?v=oI_X2cMHNe0) which includes an actual physical experiment and some discussion of the surface-charge model of what causes current to flow in non-superconductors. Oh, that's the video the OP linked; we've come full circle :P $\endgroup$ Mar 9 at 5:13
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Current is indeed the flow of electrons or other charge carriers, however, the charges flow according to the influences of the electric field experienced by the individual charge carriers (e.g. electrons). When an electric field is applied to a conductor, for example, the electrons in the conduction band will move according to the influence of the applied electric field.

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Usually, an electric current is the flow of electric charges (= electrons, ions, or positive pseudoparticles within a p-type semiconductor). However, this is not the full story.

The complication is that you can have a current through a capacitor. A capacitor in its simplest form is just two conductive plates separated by an insulator. When you connect a battery to the two plates, an electric current will flow through the capacitor until the capacitor is charged to the potential the battery provides. Note, that an electric current seems to pass through the insulator, even though no charged particle does. Instead, the electric charges literally pile up at the surface of the two plates, unable to move through the isolator.

However, while the current is flowing through the capacitor, we have a changing electrical field within the insulator. And that changing electrical field induces the same kind of magnetic field around the capacitor as the flow of charges through the wires connecting to the capacitor.

So, in a way you can say that an electric current is whatever induces a magnetic field around itself. Whether that's a flow of charged (quasi-)particles or a changing electric field does not matter.


The setup within the film has two long wires with a constant distance between them. And the combination of wire-air-wire acts as a capacitor in this case, allowing a small current to flow between the two wires while the electric field between them is established.

Btw, I believe it's quite normal to be confused when you first see this excellent film. It takes a while to wrap your head around it if you've never thought about the role of electric/magnetic fields within electrical circuits. But once you understand the points made in this film, you will have a much deeper understanding of electricity, moving charges, and electromagnetic fields.


Going off on a tangent, the difference between a capacitor and a wire is the fact that the capacitor stores energy within its electric field. And it releases this energy when the capacitor is discharged.

Further analysis shows that the energy flows from the sides into and out of the capacitor, not through the plates. It flows through any space where both an electrical and a magnetic field is present. And that is generally never within a wire. Because within a wire, the electrons quickly move to eliminate any electric field. The electric field exists on the outside, and when a current is present, also a magnetic field, and thus energy is transported.

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There's a definitional problem here, that the commonly used word "electricity" isn't well-defined, because electricity is not a substance. "Electrical current" is well defined: the definition of electrical current is the flow of charge.

Now, it is also possible to transfer energy (and therefore power) through either free space or a conductor by electromagnetic fields. This does not require any charge carriers to move from one to the other, and indeed moves much faster than the charge carriers.

(Do not post whole videos as questions; post specific sentences from the video as text, and/or provide a timestamp)

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Both a flow of charge and a change in an electric field count as current.

In your question you mention "an electric field along a conductor". Since a conductor (by definition) contains mobile charge, an electric field along a conductor will always result in a flow of charge, so we cannot separate those two things.

The presence of electric field in an insulator does not require current, however a change in that electric field does. That is what happens in a capacitor as charges accumulate on the two plates. The changing field between those two plates is also a form of electrical current.

The mathematics of flowing charge is simpler than that of changing fields, so that is why electrical current tends to be taught that way at introductory (high-school) levels. This understanding of current is enough to cover topics such as Ohm's law, KCL, KVL, etc.

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The combination of the words 'Is' and 'actually' triggers me into answering philosophically that 'actually' we don't know. The formulations of electromagnetic fields as well as the concept of electrons are models that we use to (quite successfully) describe our physical environment.
As far as I know the only justification we have for posing the existence of an electric field is that "something must be pulling those electrons, let's call it a 'field'". In my view it's accepted as a consensus model because 'it just works'.
The same applies to the corpuscular model of the electron: it just works. While 'actually' the electron seems to be a phenomenon emerging from the Schroedinger equation.
So in my opinion we can model the flow of electrical energy in a conductor both with the charged particle model as well as with the EM field model, but actually we have no idea.

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