superconductors dissipating power...

Discussion in 'Physics' started by scythe, Sep 9, 2009.

  1. scythe

    Thread Starter Active Member

    Mar 23, 2009
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    Hi, just a question I thought of reading a text. I know that most conductors heat up with an increase in the power going through them. I suppose this is due to electron collisions occurring within the substance. My question is about superconductors. Since a superconductor has no resistance, wouldn't you be able to send a vast amount of power through it without it heating up? Anybody know?
     
  2. ELECTRONERD

    Senior Member

    May 26, 2009
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    A superconductor has no resistance, and therefore nothing that will dissipate energy in the form of heat, which resistors do. Thus, superconductors shouldn't heat up, but the components are another thing. All semiconductors dissipate heat, but if they had no internal resistance that wouldn't be so. I've heard that at absolute zero, something like this can be achieved, although that is an indeterminate conjecture.
     
  3. scythe

    Thread Starter Active Member

    Mar 23, 2009
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    I thought so! Thanks!
     
  4. Wendy

    Moderator

    Mar 24, 2008
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    Superconductors generate no heat. Superconducting components will generate no heat (such as transistors made of the same material). What limits superconductors is magnetic fields, you hit a certain field strength and the material stops being a superconductor.
     
  5. Skeebopstop

    Active Member

    Jan 9, 2009
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    Electrical energy (current if you will) actually travels 'differently' than normal under superconducting conditions. Rather than the usual jostling of electrons, electrons actually travel in what are called 'cooper pairs' through a superconducting medium which guarantees they do not interact with the materials crystal lattice (this is why not all materials will ever be superconductors as they don't form an appropriate lattice for cooper pair formation - as ELECTRONERD said, silicon is not one of these such substances).

    Recently a group in china I believe has created a material which super conducts @ 55K (absolute zero + 55 degrees). The aim here is to get superconductors which operate at room temperature and completely shift the way the modern world works.

    Personally I have a hunch that superconductors are pretty bad ass, but if we were physically able to put enough current down them, they too would burn up, however you must consider 'how' you would do this. The only way we currently can is with a 20 meter wide cable running a couple million amperes, however how would we connect a 20 meter wide cable to a 20mm superconductor cable? We couldn't and the junction point itself would NOT be a superconductor and as it narrowed would explode from heat. The reason I have this hunch is that cooper pair formation requires two electrons (or so the current theory holds) to 'pair up' and since there are a 'finite' number of electrons, if we were able to physically use them all up in pairing, any additional potential we attempted to blast down the line would result in the material to be torn apart proton by proton.

    Somehow I feel I must be talking crap, but it seems like it has to be this way?
     
  6. Wendy

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    Mar 24, 2008
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    The number of electrons is so large that finite is not a valid concept in this case.

    Thing I wonder about is if it does stop conducting with a certain magnetic density does using a larger cable disperse the concentration of the magnetic field? I'm betting it does a bit, but maybe not as much as we'd like.

    One of the concepts "out there" is using a ring of superconducting materials, possibly circling a power plant, insulated by blocks of aluminum that would normally be considered conductive. This ring can store a lot of electricity for a long period of time as a magnetic field. If the superconductor fails for any reason all that stored energy would be converted into heat (mmm, maybe weapons idea there) and be soaked by the aluminum, which would also conduct the electricity while it goes to heat (instead of lightning).
     
  7. Skeebopstop

    Active Member

    Jan 9, 2009
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    The 'finite' number of electrons is exactly it. With enough current, and as you say magnetic field, there must be something which 'saturates' the superconductivity and thus tears the material apart. Obviously this is probably more than the megaamperes range.

    What you just said could also be very useful for solar cells. The most difficult thing with solar technology is to store it up efficiently enough to power the household all night. Currently the top technology are H2 and O2 catalytic converters using platinum to split them, allowing them to reform as H2O and in the process giving off a pretty efficienty amount of energy.

    A superconductor as you say could be a nice way to achieve this and store up lots of energy in the magnetic field. I wonder what would happen if this 'ring' were replaced with a very tightly wound coil (inductor). This would probably allow for much more to be stored? Wouldn't aluminum, as in iron, also be slightly susceptible to eddy currents and thus some magnetic storage inefficiency? Obviously air also wouldn't be 100% efficient for magnetic storage but probably quite good.
     
  8. Wendy

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    Mar 24, 2008
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    If you increase the magnetic field with more coils you just hasten when it will fail. As I understand it it is a field density issue. Instead of more coils, you widen the diameter (which is already pretty wide if it is circling a building) to store a low amount of flux over a bigger area.
     
  9. Skeebopstop

    Active Member

    Jan 9, 2009
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    I hope nobody is out lost in the woods anywhere near this power plant or their compasses will not point north.
     
  10. Wendy

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    Mar 24, 2008
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    Last edited: Oct 5, 2009
  11. Skeebopstop

    Active Member

    Jan 9, 2009
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    I wonder what temperatures they predict their metal can superconduct until....

    It almost seems like super conductors of opposing polarities and some special rigs could be used to accelerate space craft from the surface.

    I require immortality to see how all of these discoveries go!
     
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