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RPM, Magnetic Strength and Coils ?

Discussion in 'Electronic Basics' started by [email protected], Feb 5, 2006.

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  1. Guest

    What is the formula that determines the power output one would expect
    to get by rotating a magnet within a coil ? Say I have a coil with 100
    wraps and a magnet at 1 Gauss and I rotate that magnet at 1000 rpm
    within the coil... what will be my power (voltage and amp/watt) output
    ?

    1. IF I KEEP ALL THE SAME:
    But double the MAGNETIC GAUSS (to 2 GAUSS) how much more power output
    can I expect ?

    2. IF I KEEP ALL THE SAME:
    But double the RPM of the magnet (to 2000 RPM) within the coil, how
    much more power output can I expect ?

    3. IF I KEEP ALL THE SAME:
    But double the coil (to 200 wraps), how much more power output can I
    expect ?

    I'm trying to understand the ratio and relationship (in power output)
    between RPM, Magnetic Strength and Coils.

    Thanks,
    J.
     
  2. Guest

    Just as in other cases SIZE MATTERS!!
     
  3. Guest

    Thanks CBarn -- Can you formulate how "SIZE MATTERS" in regards to my
    questions ? An Atom contains the smallest particles known, for not
    exist atoms there would be no "size" -- nothing greater than "the
    nothingness" -- therefore I propose that it's the tiny that matter, for
    without them there would be nothing bigger.
     
  4. Bob Monsen

    Bob Monsen Guest

    Faraday's law of induction points out that you can get a *voltage* if you
    change the magnetic flux through a coil. The formula is

    V = N * dF/dt

    where F is the magnetic flux in webers, and N is the number of turns in
    the coil. Unfortunately, you can't directly relate gauss to webers
    unless you know the geometry of the situation.

    So, given my shaky understanding of the subject, I believe that you can't
    know the power with the information given for several reasons:

    voltage cannot be related to power without knowing the impedance.

    You don't know the rate of change of magnetic flux, because we can't
    calculate the flux without knowing the geometry.

    That being said, you can see that if you double the magnetic flux density,
    then the rate of change of flux as the coil rotates will double. This
    means that the induced voltage will double, and since power is related to
    the square of voltage, the power transferred will quadruple.

    Doubling the RPM will also double the rate of change of flux, causing the
    same result.

    Doubling N will again double the voltage, causing the same result...

    --
    Regards,
    Bob Monsen

    "I am a strong advocate for free thought on all subjects, yet it
    appears to me (whether rightly or wrongly) that direct arguments
    against christianity & theism produce hardly any effect on the public;
    & freedom of thought is best promoted by the gradual illumination of
    men's minds, which follow from the advance of science. It has,
    therefore, been always my object to avoid writing on religion, & I
    have confined myself to science. I may, however, have been unduly
    biassed by the pain which it would give some members of my family, if
    I aided in any way direct attacks on religion"
    -- Charles Darwin
     
  5. Guest

    Thanks Bob
     
  6. Rich Grise

    Rich Grise Guest

    . ;-)

    What you're talking about is indistinguishable from magic - there is no
    formula, it's by-guess-and-by-gosh, and the people who have been making
    motors and generators for centuries now keep their tools and techniques
    a closely guarded secret.

    Good Luck!
    Rich
     
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