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Electric Potential Earth and Sun?

  1. Jun 28, 2009 #1

    NJV

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    Reading about Velikovsky's pseudoscience, I wondered what the values of the Earth and sun's electric potential really are?
     
  2. jcsd
  3. Jun 28, 2009 #2

    LURCH

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    Never really thought about it before, but the Sun should be very strongly charged. It is mostly plasma, meaning protons without electrons orbiting them. I don't know how many of those electrons are ejected into space as radiation, but I know that some are. This should leave the Sun with a very strong positive charge (relatve to Earth).

    Now, I'm going to do a search on Velikovsky, to find out what you're talking about.
     
  4. Jun 28, 2009 #3

    NJV

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    Velikovsky believes that Venus was ejected from Jupiter and similar peculiarities, based on ancient mythologies. It's kind of interesting, but not scientific.
     
  5. Jun 29, 2009 #4
    The sun and the earth, I would imagine, are both electrically neutral to an enormous degree of precision. If even a fraction of a percent of the sun's mass was not neutral the electric attraction it would exert (even on neutral objects) would far outweigh its graviational attraction. The sun may be mostly plasma but that just means that the electrons aren't attached to a particular proton it by no means suggests that there are more electrons then protons present.
     
  6. Jun 29, 2009 #5

    Vanadium 50

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    Yes, and so are protons. This makes the sun electrically neutral to a very good approximation.

    Think about it. Once an electron is ejected, the sun becomes positively charged, and it becomes that much harder to eject the next electron, and that much easier to eject the next proton. Furthermore, it will be that much more likely to capture a passing electron and that much less likely to capture a passing proton. The system will very quickly reach an equilibrium.
     
  7. Jun 29, 2009 #6

    NJV

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    Yes, I thought that too when I read that. Although then again, protons have far greater mass and therefore require more energy to be expelled. Furthermore, despite its heat the sun isn't all fluid, with the core having a density 150 times that of water. I've read photons take about a million years to travel from the core to the surface. With such separation between core and surface, there might very well be a difference between the outer and inner layers. Of course there are relative potential differences in almost any spherical body, but I want to know what its potential relative to other spherical bodies would be.

    (Of course Velikovsky was wrong and electromagnetism obviously plays no observable role in the movement of the planets.)
     
  8. Jun 29, 2009 #7

    diazona

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    Actually about 100,000 years, if I remember correctly... not that it matters much.

    Anyway, unless you're doing very high-precision measurements I would think you could assume the Sun's potential to be zero. :-/
     
  9. Jun 29, 2009 #8

    NJV

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    Hm. Has that in any way been verified? It would certainly debunk Velikovsky's myths. A friend of mine is fascinated by them.
     
  10. Jun 29, 2009 #9
    because the universal gravitation constant G is over the order 10^-11 and the coulomb constant k is of the order 10^9. That means if there was even a single coulomb of free charge it would generate as much force as 10^20 kilograms! and the sun only weighs 10^30
     
  11. Jun 29, 2009 #10

    NJV

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    I suppose that decisively settles it. Thanks for your reply, starstrider!
     
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