Electric currents and length contraction

In summary, the conversation discusses the concept of relativity theory length contraction and its explanation of magnetic fields. The image provided shows the effect of a -I current into a neutral wire producing a magnetic field B and a force Fm on q. The question arises as to why, in the S system, the moving of electrons does not result in length contraction of their electron-electron distances and an electric force Fe on q. The answer provided by DrGreg suggests that the wire is neutral because the distances between electrons are the same as the distances between protons in a frame where they are at rest. The conversation also touches on the interesting effects of relativity during the transition from a neutral wire to a steady current.
  • #1
Luis Babboni
Hi people, me bother yo again!

I understand that relativity theory length contraction is the explanation of magnetics fields.
See the image:
densidadcargasencorriente.jpg

https://dl.dropboxusercontent.com/s/vuy69jhig3kni3n/densidadcargasencorriente.jpg?dl=0

1) In the S system, if q is moving at the same velocity than the electrons that made the current, the -I current into a neutral wire produces a magnetic field B that make a force Fm on q.
2) It can be explained what happens in 1) from what happens in a system S´ that is moving at the same velocity than electrons and q. The length contraction of proton-proton distances made the wire not even more neutral so q, at rest in S´, feels an electric force Fe.

My question is why in S, as I show in 3) the moving of electrons do not result in length contraction of theire electron-electron distances making the wire not neutral and then an electric force Fe appears on q?

In this case I think I have the answer but not sure if it is correct and then I ask you about it:

Is cause "a neutral wire in S" is neutral because the main distances electron-electron in a frame where electrons are a rest is the one needed to make those distances are the same as proton-proton distances in a frame where protons are at rest?

Thanks!

PS: In the case my answer is correct, the trasient from neutral wire without currents to steady current in it, would be interesting in terms of relativity effects! I´m right?
 

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  • #2

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Likes vanhees71
  • #3
Nice! Thanks.
 

What is an electric current?

An electric current is the flow of electric charge through a conductive material. It is typically measured in units of amperes (A) and is caused by the movement of electrons within the material.

How does electric current affect length contraction?

According to Einstein's theory of relativity, objects in motion experience length contraction, meaning they appear shorter in the direction of their motion. Electric current can affect this length contraction by producing a magnetic field, which can interact with the electric field of the moving object and alter its length contraction.

What is length contraction?

Length contraction is a phenomenon described by Einstein's theory of relativity, where objects in motion appear shorter in the direction of their motion. This is due to the time dilation effect, where time appears to slow down for moving objects, causing their length to appear shorter from a stationary observer's perspective.

How does the speed of an electric current affect length contraction?

The speed of an electric current does not directly affect length contraction. However, the speed of the electrons within the current can contribute to the overall speed of the object and therefore affect its length contraction.

What are some real-life applications of electric currents and length contraction?

Electric currents and length contraction have many practical applications in modern technology, such as in particle accelerators and MRI machines. They also play a role in the functioning of electronic devices and the development of high-speed transportation systems.

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