# Electric Field from overhead lines

Discussion in 'Homework Help' started by Cerkit, Nov 14, 2012.

1. ### Cerkit Thread Starter Senior Member

Jan 4, 2009
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3
Hi. I am not too sure about the electric field from AC overhead lines, I understand an electric field from a charged particle but not too sure when there are electrons moving back and forward quickly as in AC what the field looks like??
Can someone please explain to me what the electric field from overhead lines looks like, is it just away from the conductor core radially (can anyone refer me to a diagram for this) and why is it so. Is the electric field alternating ? Do you need current to flow for the field to exist or does it exist just with a potential?

2. ### JoeJester AAC Fanatic!

Apr 26, 2005
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Here are the graphics

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3. ### bountyhunter Well-Known Member

Sep 7, 2009
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Yes, because the voltage is alternating.

4. ### Cerkit Thread Starter Senior Member

Jan 4, 2009
284
3
Ok. So would it be correct to say that there is an electric field (albeit weaker) a fair distance away from a current carrying conductor because of the electromagnetism? Would it be correct to view it like that in the sense that the electric field exists as a result of the propagation of the magnetic field surrounding the conductor?
I guess the concept of the electric field existing a certain distance away from a conductor is just hard to understand intuitively.

5. ### crutschow Expert

Mar 14, 2008
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Not really.

Magnetic fields are generated by current flow in a wire and are proportional to the amount of current.

Electric fields are generated by and are proportional to the potential (voltage) in a wire and are independent of current or the magnetic field.

Both decrease with distance from the wire.

If the voltage in a wire is alternating, then so will the associated electric and magnetic fields.

Of course an alternating electric and magnetic field also generates an electromagnetic (radio) wave which propagates through space to a much greater distance then the magnetic and electric field do.

6. ### bountyhunter Well-Known Member

Sep 7, 2009
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But magnetic fields are a lot harder to shield......

7. ### Cerkit Thread Starter Senior Member

Jan 4, 2009
284
3
Ok. But what actually constitutes of the electric field, how does the electric field exist lets say several metres away from the overhead line, if I hypothetically placed an electron a few metres away from the overhead line what (is the physics behind it that) makes the electron to be pushed/pulled according to the electric field??

Apr 28, 2012
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9. ### MrChips Moderator

Oct 2, 2009
16,874
5,181
Sometimes we pull up our sailboats on to a beach where there are HV transmission lines very high overhead. I talking about those huge power transmission pylons.

If you were to touch the metal masts or stays of the sailboats you would get an electrical shock.

10. ### Cerkit Thread Starter Senior Member

Jan 4, 2009
284
3
But what actually constitutes of the electric field, how does the electric field exist lets say several metres away from the overhead line, if I hypothetically placed an electron a few metres away from the overhead line what (is the physics behind it that) makes the electron to be pushed/pulled according to the electric field??

Oct 2, 2009
16,874
5,181