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Discussion in 'Electronic Basics' started by [email protected], Jul 1, 2007.

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  1. Guest

    Hello everybody,
    I am new in here and i am a 6th grader. i wonder if u could help me.
    U see i have been asked for a couple of times that why can't we build
    a 100% efficiency power electonic generator. Hope you can help me.
    its an emmergency! My exams r near. Please help me.

  2. Eeyore

    Eeyore Guest

    Think about electrical resistance and the effect it has.

  3. Generators do not produce energy, they convert mechanical
    energy to electrical energy. Every conversion process
    includes some wasted energy. For instance, just spinning
    the rotor of the generator involves the drag of air on the
    rotating part, and the friction in the bearings.

    Operating the generator in a vacuum would eliminate the loss
    to air drag, as a possible improvement, but the air also
    helps to carry away the heat produced by current passing
    through resistance of the generator windings. The hotter
    the windings get, the higher their resistance, so the more
    energy is wasted in that part of the process. So
    eliminating the air in the generator makes one loss lower,
    and one higher. Good engineering involves optimizing the
    overall blend of losses, so that the overall efficiency is
    maximized. But 100% is never possible.

    You might have to get into the physics of irreversible
    processes to put that fact on a mathematical basis.
  4. Charles

    Charles Guest

    I'll assume that you mean an electric generator that is a rotating machine.
    Turning the shaft means that one must overcome bearing friction ... that's
    only one loss which precludes 100% efficiency. Other losses are:

    resistance loss in the coils/windings
    magnetic losses in the iron cores of the rotor and stator (eddy currents and
    hysteresis loss).
    air resistance (as it rotates, it is obliged to shove air molecules aside)
  5. Aly

    Aly Guest

    For God's sake don't answer the exam questions in text speak. Sort out your
    spelling too.

    While I've never ascended (descended?) to the level of NetNanny, if you are
    looking for advice then it applies here.

    YOU WILL lose marks. Language is above everything.

    Oh, and we can't build a 100% efficency power electronic generator as we do
    not live in a perfect world. I could mention Tesla but that's something for
    another time.
  6. Jasen Betts

    Jasen Betts Guest

    electrical resistance
    leaking magnetism

    beat those three and you'd probably be able to do it.
  7. neon


    Oct 21, 2006
    if you do that let me know you are the first humanoid to biuld the perpetual moving machine. moron
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