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Janez
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I have a question what does create a electric filed inside coducting wire? And is it the same field trought the whole wire? Thanx for answers.
Janez said:I have a question what does create a electric filed inside coducting wire?
Janez said:And is it the same field trought the whole wire? Thanx for answers.
Janez said:No I meant electric field. I know there is potencial diffrence between ends, but ther is also electric field insede wire. And electric fieled is a field so it is evrywhere, just sometimes its value might be zero.
The formula is I/A = σE. If σ=∞ (perfectly conducting wire) then E will be zero. If the wire has resistance then the formula is IR = d(Es + Em) where d is the length of the wire of resistance R.Meir Achuz said:"And is it the same field throughout the whole wire?"
The current in a wire is I=V/R. The electric field at any point in the wire is [itex]E=I\sigma/A[/itex], where [itex]\sigma[/itex] is the conductivity, and A is the cross-section area of the wire. If A is constant, E is constant. If A varies, E~1/A.
Hello @Delta2,Delta2 said:@rude man can we say that the field you call ##E_m## is the electric field component due to the vector potential and the ##E_s## is the electric field component due to the scalar potential?
Em is not a magnetic field component, it's an electric one.Delta2 said:By vector potential I mean the magnetic potential ##\vec{A}## (which is a vector with 3 components) such that ##\vec{B}=\nabla\times \vec{A}## and ##\vec{E}=-\nabla V-\frac{\partial \vec{A}}{\partial t}##
So ##E_s=-\nabla V## and ##E_m=-\frac{\partial \vec{A}}{\partial t}## that's what I meant.
I suggest looking at some of the other items in the bibliography, I thought Krauss gave a good account and he was an E&M expert. Some of the others are intense in their treatment of the subject with vectors and so on. I thought it interesting that one of the earliest articles was from 1963.rude man said:The amasci paper is very good.
Might have included what goes on inside the wires as well: inside the wire the E field is entirely parallel to the flow of current (the charges are on the wire surface so the larger external E field is mostly normal to it).
If the wire resistance is not zero there is a small component of the P vector normal to the wire surface; it enters the wire and is dissipated by the time it reaches the center of the wire axis. There is also a small E component tangential to the wire equal to the E field within the wire.
The main point remains the fact that most of the power flow is tangential to the wire and thus to the E field inside the conductor, and the current. That's what a wire is usually for: to guide power along it.
EDIT: after reading the pertinent secion of Feynma's Chapt. 27 I think amasci has misrepresented what Feynman says. I quote: "You don’t need to feel that you will be in great trouble if you forget once in a while that the energy in a wire is flowing into the wire from the outside, rather than along the wire. It seems to be only rarely of value, when using the idea of energy conservation, to notice in detail what path the energy is taking." And "It is not a vital detail, but it is clear that our ordinary intuitions are quite wrong."
In other words, Feynman clearly states that the idea of energy propagating with the current is wrong, but that "forgetting" it does not usually lead to energy conservation errors.
A battery contains two electrodes, one positively charged and one negatively charged. When connected to a wire, the electrons from the negative electrode are pushed towards the positive electrode, creating a flow of electric current. This flow of electrons creates an electric field inside the wire.
The strength of the electric field inside a wire depends on the voltage of the battery and the resistance of the wire. A higher voltage or a lower resistance will result in a stronger electric field.
The electric field inside a wire acts as a force on the electrons, pushing them in a specific direction. This force is what causes the electrons to flow through the wire and power devices.
Yes, the electric field inside a wire can be changed by altering the voltage of the battery or by changing the resistance of the wire. Additionally, the direction of the electric field can be changed by reversing the polarity of the battery.
The main danger of working with batteries and electric fields is the risk of electric shock. It is important to handle batteries carefully and to avoid touching exposed wires or conductors. Additionally, batteries can overheat and cause fires if not used properly.