How do electrons flow in a circuit?

In summary, the electric field in a wire is changing direction along the direction of the wire. This causes the flow of electrons.
  • #1
rootX
479
4
I know how they move in vacuum when some positive/negative charge is near them.
But I have found it really difficult to visualize their movement in a wire.
First I used to think that due to the presence of electric field, they move from the negative terminal to the positive. But as the wire can bend, and so it doesn't make sense since electric field are straight lines.

So, I tried this model:
Near the positive terminal, valence electrons are being attracted, and thus the atoms that are near the positive terminal become positive, and they attract electrons from the remaining part of the wire.

This sounds more correct, but according to this, all part of the wire from the switch to the positive terminal should be charged positive when the switch is open, and that doesn't make sense.

Can anyone provide me the correct model?

This have been bugging me for a lonnng time. :frown:
Thanks a lot!
 
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  • #2
rootX said:
I know how they move in vacuum when some positive/negative charge is near them.
But I have found it really difficult to visualize their movement in a wire.
First I used to think that due to the presence of electric field, they move from the negative terminal to the positive. But as the wire can bend, and so it doesn't make sense since electric field are straight lines.

It is the electric field that causes the flow of electrons... the electric field in a bent wire is changing direction along the direction of the wire...
 
  • #3
Who said the electric field is always composed of straight lines? As soon as you bring a conductor into an electric field, it's sure as heck not going to be straight anymore!

- Warren
 
  • #4
Another way to think about this is to remember that real wire has some finite resistivity. If you measure the potential along a wire that connects a + and - terminal, there will be a gradual voltage drop all along the wire. Like, if you connect a 1.5V battery to long wire (that say has 10 Ohms of resistance because it is long and skinny wire), then you will get 150mA of current flowing through the wire. The "current" flows from the + terminal to the - terminal, and the actual physical electrons are flowing in the opposite direction.

Now, if you go along the wire and measure the potential with respect to the - terminal, you will see a linear drop in voltage along the wire, from 1.5V at the + terminal, all the way down to 0V at the - terminal. Now think of a cross-section of the wire at one spot. If you think of a plane cutting through the wire, that is an "equipotential surface", at the potential that you measure with your voltmeter. So there are an infinite number of little disk-shaped equipotential surfaces stacked all along the length of the wire.

Now, you know that the direction of the electric field vector E is normal to an equipotential surface, right? So that tells you how E bends along with the conducting wire, always pointing down the wire. Does that help you to visualize it?
 
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  • #5
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  • #7
u should look into some of my threads ...many of them have to do with the flow of electrons in a circuit very beautifully explained and also the links provided.:wink:
 
  • #8
thnx.a lot
I will have look at them(they seem to have really good explanation!).

P.S.
pardesi,
just found that Irodov's "General Problems in Physics" thread. I was looking for this kind of book for a really really long time. So thanks again/
 
  • #9
welcome have great time solving it :wink:
 

1. How do electrons flow in a circuit?

In a circuit, electrons flow from the negative terminal of a battery or power source, through a conductive material such as a wire, and ultimately to the positive terminal of the battery. This flow of electrons is known as an electric current.

2. What causes electrons to flow in a circuit?

The movement of electrons in a circuit is caused by the presence of a voltage difference between the positive and negative terminals of a battery or power source. This difference in voltage creates an electric field, which pushes the electrons through the circuit.

3. How do electrons move through the different components in a circuit?

Electrons move through a circuit by following the path of least resistance. This means they will flow through conductive materials such as wires and resistors, but will avoid non-conductive materials such as insulators. The flow of electrons can also be controlled and directed by components such as switches and diodes.

4. Can electrons flow in a circuit without a power source?

No, electrons require a voltage difference created by a power source in order to flow through a circuit. Without a power source, there is no electric field to push the electrons and no current can be produced.

5. What is the role of electrons in a circuit?

Electrons are the carriers of electric charge and their movement through a circuit is what creates an electric current. This current is essential for powering electronic devices and allowing them to function properly.

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