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Parallel conducting currents and the relevance of reference frames.

  1. Oct 15, 2008 #1
    i've just had this thing running through my head that i'm trying to resolve:

    1. two parallel wires that conduct a current (same charge carriers) will attract one another, that is the magnetic force each wire emits due to the flowing current will induce an attractive force in the other (charge carriers in the) wire.

    2. this would be true also for two parallel beams of emitted electrons for example, and the attractive force would cause these two beams to merge and become one. or would there be a limit where the attractive magnetism is cancelled / balanced by the repulsive electric charge?

    with this in mind i was thinking:

    3. might this partially explain very early planet formation in the solar system - e.g. the formation of dust grains from gas molecules? for example, intense radiation from the early sun strips some atoms of an electron and . . . becasue these negative charge carriers are now moving in the same direction (essentially parallel at their scale, but actually due to their orbit around the sun) they begin to accumulate and form larger particles whose size grows until they start to stick together under gravity for example.

    but then i got thinking:

    4. relative motion. these gas molecules are only moving in their orbit relative to the sun, or, arguably relative to the galaxy / rest of Universe / observer "above" the solar system. the gas molecules themselves - or plasma molecules if stripped of an electron - relative to each other are not really moving at all, it is the sun and universe outside the solar system that is moving. but this scenario also applies equally back to our parallel conducting wires.

    so . . .

    5.1 if they are not moving relative to each other then the electric force dominates and their positive charges repel?

    5.2 but they are moving relative to the sun and so they attract?

    5.3 is the reference frame for the solar plasma and the wires actually fundamentally different with plasma actually continually changing velocity (due to circular orbit) having some influence?

    i have thought myself into a cul de sac and don't yet know how to resolve this and get out.

    can anyone help?

    ps: i realise that actual solar and plasma dynamics will in reality be very complicated but if we can just consider an "ideal" clean scenario?
  2. jcsd
  3. Oct 15, 2008 #2
    Electrons repulse each other because the electromagnetic force of repulsion is billions of times stronger than the attractive force of gravity...

    It's been too long for me to comment on your example 1, I don't remeber, but in example2, free electrons will always respulse each other...so the beams will move apart.....like charges repel as they overcome the momentum after emission from a source.

    After the initial turmoil in the universe subsides and ions, electrons and atomic nuceli formed to atoms of various elements, mostly hydrogen, the gravitational attraction of the electrically neutral atoms eventually leads to star formation and fission/fusion reactions...
    Last edited: Oct 15, 2008
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