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How much is one Farad?

  1. Jan 23, 2004 #1
    This ain't no theory development but scientific facts

    In "Special theory of relativity" by dr. V.Z. Belgrade 1997 it's writen:
    [tex]c=\frac{1}{\sqrt{e_0m_0}}=3E8\frac{m}{s}[/tex] for the speed of the light;

    In "Electro-magnetics 1" by dr. Lj.J. Skopje 1994 it's writen:
    [tex]e_0=\frac{1E-9}{36 \pi} \frac{F}{m}[/tex] for dielectric const of vacuum;

    [tex]m_0=4 \pi 1E-7 \frac{F}{m}[/tex] for magnetic permeability in vacuum;

    => [tex]c=3E8 \frac{m}{F}[/tex] and 1F=1s;

    [tex]F_C=\frac{-kQ_1Q_2}{R^2}[/tex] - The Coulomb's law;

    [tex]k=9E9\frac{Nm^2}{C^2}=\frac{1}{4\pi e_0}[/tex] for Coulomb's proportionale;

    => [tex]e_0=\frac{1E-9}{36 \pi} \frac{C^2}{Nm^2}[/tex];

    => [tex]\frac{C^2}{Nm^2}=\frac{F}{m}[/tex];

    => [tex]\frac{C^2}{Nm}=F[/tex];

    => [tex]Nms=C^2=\frac{kgm^2}{s}[/tex];

    => [tex]kgm^2=C^2s[/tex];

    My question is where is the sense in that?
  2. jcsd
  3. Jan 24, 2004 #2
    I wish that you show me where I'm wrong.
    But if I'm not...
  4. Jan 24, 2004 #3


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    First, you didn't say that or ask any question in your first post.

    Second, it might help it you clarified this.

    For example, in [tex]e_0=\frac{1E-9}{36 \pi} \frac{F}{m}[/tex], what are m and F? I might be inclined to think that "m" is mass but this is supposed to be the "dielectric const of vacuum".
  5. Jan 24, 2004 #4

    these are units:
    F is Farad;
    m is meter;
    kg is kilogram;
    s is second;
    C is Coulomb;
    N is Newton;
  6. Jan 24, 2004 #5
    If you took a non-leaky discharged capacitor and charged it for one Second at a current of one Amp and at the end of the charge period measured the voltage across the capacitor and found it to be exactly one Volt, then that capacitor would have a capacitance of one Farad.


    A Farad is a unit of measure for capacitors.

    Capacitors are a bit like tiny rechargeable batteries.

    A capacitor with a capacitance of one Farad would store one Coulomb of charge when charged to a voltage of one volt.

    One Coulomb of charge is the amount of charge delivered, when one Amp flows for one second.
  7. Jan 24, 2004 #6
    I'm sure I read my book corectly but,
    I made some search on e0 and m0.
    Here is what I found:
    -electrical permittivity this one is actually in F/m (as I said)
    -magnetic permeability and this in H/m (not as I said)

    So, I guess I should also aks how much is one henry too.
    Make it easy for me.Tell me right away how much is
    squareroot(henry times farad).
  8. Jan 24, 2004 #7


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    The question you need to ask is, not "how much it 1 Henry" but What are the fundamental units of a Henry.

    Ok, now that you have asked the rigth question

    H => Volt second/Amp

    Farad => Amp Second/Volt
  9. Jan 25, 2004 #8
    There was definitly error in the book "Electromagnetics 1" that I recalled. I'm positive that's how it's writen there. I know that profesor. I might warn him some time.

    This topic is history.
  10. Jan 25, 2004 #9
    gahh im awash in a sea of units, the word Henry itself reminds me more of the King Henry's in England rather than the electric induction unit that holds its scientific name. Or it could be the orator Patrick Henry from the House of Burgesses, "Give me liberty or give me death!" Semantics playing a game with my head, and im losing.
  11. Jan 26, 2004 #10


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    It was Joseph Henry, an American physicist who was (more or less) in competition with Faraday in the electromagnetism search and did fine work. He discovered reverse induction (magnetic field producing current) independently of Faraday.
  12. Jan 26, 2004 #11
    this could get massy but i don't seem to mind

    henry times farad = anna times jesica

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