Electric field around a current carrying conductor?

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Solution 1

In a circuit involving potential drop (so, not purely a current wo/voltage,) the e-field around conductors is perpendicular and radial, and the e-field around resistors is radial with some tilt.

For conductors with arbitrarily small resistance, the flux-lines of e-field appear in the space outside the conductor, and are connecting the surface-charge with charges found upon other, distant parts of the circuit (e.g. parallel wires having opposite charge.) Here's the oversimplified visual version:

Simple circuit:

Magnetic flux, circles around wires

E-field flux, radial lines connecting surface-charge

Both together: cross product is poynting flux, energy-flow from source to sink

. Notice that the fields are those of a 2-wire waveguide or transmission line? Exactly right. The same physics applies at Zero Hz DC, and also applies at 60Hz AC, and also at radio frequencies.

Solution 2

Electric field lines describe the force experienced by positive point charge at a point. In a current carrying wire,the force experienced by a positive point charge is in the direction of current,so electric field is in the direction of current.But outside a current carrying wire there won't be any field lines as there is no electric force .

Electric field was produced inside the wire due to the potential difference created by the battery.But outside the wire there is no such thing.

Solution 3

Imagine the nature of the electric field if the wires are not next to each other. In fact imagine the wires are going in the opposite direction away from the source for miles and then at the right angle for miles and then again at a right angle back around to the load somewhere and then keeps going for miles and finally turns back at the right angle to the source. I do not know the distance between the wires in the above schematics so the field on one wire knows where to be pointing towards. How far can the field detect the other wire and how quickly it knows that it better point that way. And if it is miles and miles square and not a nice neat rectangle as in the diagram..... IT is a natural inquiry.

I say there is more involved here than we are admitting. There is an electric field along the wires for charges to move. There is an electric field also in all directions and not just between the wires. There are also other influences on the charges so to keep them from accelerating in the direction of the field which is, of course, the direction of force too. The charges also most likely have to deal with the collective magnetic field, after all, the collective field is not an individual electron's magnetic field. They are supposedly moving through the center of the collective magnetic field

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Alex

Updated on August 01, 2022

Comments

Alex 11 months

The picture shows the direction of the magnetic field around a current carrying wire. I wonder what will be the direction of the electric field with respect to the direction of the magnetic field ? I am trying to visualize both electric and magnetic field at the same time. I am getting the picture of the direction of the magnetic field everywhere but could not find any picture that shows both of them togather.

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- BowlOfRed about 5 years
  
  See also: physics.stackexchange.com/questions/61884/…
Alex about 5 years

Thanks alot for your answer. It was really great. Although i am not aware of the poyenting vector but you made many things clear to me. Is this how the electromagnetic waves look like ? they say that in an electromagnetic waves both electric and magnetic fields are perpendicular to each other. and the picture you have shown magnetic and electric field also look perpendicular to eachother.
Alex about 5 years

as the electromagnetic waves are produced by the acceleration of the charges.
wbeaty almost 5 years

Yes, DC circuits employ electromagnetic waves. But the "wave" is just one large hump, many hours wide. This is little different than 60Hz power lines, where each hump is 8.33mS wide. The fields during the middle of each hump, they look like the diagram above. Two-wire waveguides function independent of frequency, and can transmit energy at zero Hz or at 50 GHz, or anything between. PS in the above, if the wires are resistive, then the e-field isn't at right angles to the wires. It tilts slightly, as EM energy from space is moving radially inwards to the wires, becoming heat in metal.