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Units of 1/Farads and 1/Henries?

Discussion in 'Electronic Basics' started by Joel Kolstad, Oct 30, 2004.

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  1. Joel Kolstad

    Joel Kolstad Guest

    Just curious... the untis of the inverse of an Ohm are a Mho (cute). Is
    there an equivalent for the inverse of Farads and Henries? I realize that
    most of the time you're after the impedance broken into the resistance and
    reactance (units: ohms) or the admittance broken into conductance and
    susceptance (unit: mhos), but I figure there's a good chance someone named
    1/Farads and 1/Henries at some point in time.

    ---Joel Kolstad
  2. Rich Grise

    Rich Grise Guest

    What would they mean?

  3. Joel Kolstad

    Joel Kolstad Guest

    Nothing physically, just an 'interim' unit if you want to talk about, say,
    parallel inductors or series capacitances.

    Apparently I'll just stick with F^-1 and H^-1...

  4. Joel Kolstad

    Joel Kolstad Guest

    But writing an upside-down Omega is so much fun!

    Do you have anything that suggests Mho is actually deprecated rather than
    simpler synonymous with Siemens?

  5. The SI system is the international scientific and technical standard in
    the modern world. There is no Mho in that system.

    We should avoid all older or regional units and use the SI system to
    simplify understanding and education in a global perspective.
  6. Joel Kolstad

    Joel Kolstad Guest

    Fair enough...

    It is amsuing that the English have switched to SI whereas the US hasn't
    yet! ;-)
  7. Clarence

    Clarence Guest

    An Engineer worth his salt should be able to work in any system presented.
  8. Hi,

    The reciprocal of 'Capacitance' is 'Elastance' which comes
    from the similarity to the spring constant. It is measured in
    'Darafs' would you believe.

    The reciprocal of 'Inductance' is sometimes given as 'Reluctance'
    but you have to do a dimensional hand-stand to accept it.

    Cheers - Joe
  9. Joel Kolstad

    Joel Kolstad Guest

    True, but statistically speaking there are going to be more mistakes when
    engineers have to work in multiple systems. There are good examples out
    there of very large dollar systems such as satellites failing due to this
  10. Joel Kolstad

    Joel Kolstad Guest

    Thanks Joe!
  11. Don Kelly

    Don Kelly Guest

    Not that I know of. However, the 1/Ohm, or what was called a "mho" is now
    officially called a "Siemen". It is possible that someone, somewhere uses a
    Daraf or a Yrneh but why?
    Susceptance (-1/2*pi*f*L or 2*pi*f*C) is in Siemens. (mhos If you don't want
    to change habits)
  12. Don Kelly

    Don Kelly Guest

    Are your texts all out of date? The Siemen is used in US engineering texts
    and literature.
  13. Joel Kolstad

    Joel Kolstad Guest

    I meant in general... when you go to the store to buy furniture in the U.S.,
    the dimensions are in inches/feet/etc.

    On the technical side, if you look at magnetics manufacturers, many of them
    still use slightly non-SI units... it's apparently a slow industry to
    change. (I was at a seminar once where the speaker mentioned, "You have to
    realize, they're basically just selling you a bunch of processed dirt..."
    :) )

  14. Don Kelly

    Don Kelly Guest

    Sure and I calculate my gas consumption in miles per gallon- translating
    from liters/100km. even though I have been using metric units for 50 years
    and SI since it came into official play. My tape measure still is in inches
    and feet and I am in an officially SI country next door north from you.
    However, dealing with Gauss instead of Tesla is not a problem- I just
    convert and carry on. Lines/sq. inch -oops-what is the bugger factor?
    At least we don't play around with abvolts, abamperes or statvolts and
    statamperes. :)
  15. Brian Oakley

    Brian Oakley Guest

    another way to conform our government to the rest of the world
  16. Don Kelly

    Don Kelly Guest

    What has the government to do with it. It makes good sense. Good sense and
    government rarely go together.
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