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Frequency vs, Resistance

  1. Dec 29, 2005 #1
    Does anybody know if the Resistance changes in the flow of Electrons when the Electrical frequency increases or decreases.

    Lowest end frequencies to the Highest end Frequencies.

    For both AC and DC.

    Is there a chart?:smile:
  2. jcsd
  3. Dec 30, 2005 #2


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    Resistance is independent of frequency, but reactance is frequency dependent.
  4. Dec 30, 2005 #3


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    Another term for it is Impedance. The Impedance of a circuit has three components: The DC resistance which is the fixed minimum, then Inductive and Capacitive Reactance which add vectorial and vary with frequency. The vectorial addition of the Reactive components is generally handled as a phase angle in the imaginary plane.
  5. Dec 30, 2005 #4
    Does the Sin Wave Amplitude (Narrow to Wide) change the resistive flow of Electrons in a known conductor of a fixed Ohm?

    Seems like the Electrons would have less resistance with a narrower Sin wave Amplitude.

    It seems like if an Electron had Zero Amplitude (True Linear) it would flow through a circuit with less resistance by making a narrower path between local conductive Electrons with less interference.

    Or am I chasing my tail?:smile:
    Last edited: Dec 30, 2005
  6. Dec 30, 2005 #5


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    Did you mean wavelength (inverse of frequency) instead of amplitude (size of signal)?

    The impedance (sum of resistive and reactive) is going to vary with frequency for pretty much any conductor, even the specification sheets for wire will list the DC resistance, inductive, and capacitive properties.

    Since electricity is more logical as the flow of the wave, where each individual electron may impart its energy onto its neighbors like dominos, the behavior of an individual electron isn't really too important until the temperature is cold enough that superconduction occurs (at which point they start to pair up and 'share' the resitance).

    There are, of course, many exceptions like the skin effect that occurs at extremely high frequenices (the electron flow happens at the outside of the conductor, it acts more like a hollow wire) where something like Litz wire is used to maximize the skin area by having many seperate individually insulated conductors nearby. Or like a biflar winding in alternate directions to minimize inductance and so on.

    Regardless, with a frequency generator and a wheatstone bridge you can measure the impedance of a component and at least accurately predict its behavior just from that measurement.
  7. Dec 30, 2005 #6

    Thanks Cliff, That answers a lot of my questions.

    I wish I had my own Scope Laboratory, That would be sweet!

    The questions I was asking were related to a thought that clicked in my mind that the Electron current itself could be manipulated to pose less resistance in/on a conductor with less resistance and that Cooper pairing may not be needed to pose less resistance.

    I have some very good Periodic Tables that show good detail about conductivity and Electron Orbitals, Like Silver, A fairly exceptional conductor having only one Electron in its most outer orbit, This would seem that having only one outer Orbital would allow it to be a good conductor because there is less electron resistance in only having one outer orbital, Then things get botched up when the thought of cooper pairing takes place because now there are two Electrons that buddy up which conflict with the single orbital resistance thought.

    But then I start thinking that the cooper pairing is making the orbital field more Negative than the Electrons being conducted as current and causing the current to keep its distance from the cooper paired Atom. [Negative] <> [Negative+Negative] so the cooper pair has a stronger negative electron field and pushes the current away, this to me seems like the cooper pairs are producing some sorta of maglift effect between Atoms and allows the current to pass by the Atoms without the current hitting any local conductive electrons.

    All strange but fascinating.:smile:
  8. Dec 30, 2005 #7
    Normally you see a plot of Voltage on the vertical axis, and time on the horizontal axis. 'Amplitude' of the sine wave on this type of graph is representative of Voltage.

    I think you've got a bad mental picture of whats going on. In AC, the electrons dont follow a sine wave path. The speed of the electrons is relative to the sine wave. The electrons actually are going one directon straight down the wire when the Voltage sine wave is positive, then come the other direction when the sine wave dips negative. This is opposed to DC where the electrons all flow down the wire in one direction continuously.

    So as for the question, No. However a thicker wire does indeed have less resistance than a thin one because of more 'room' for electron travell.

    As Ive pointed out above, if the sine wave is at 0 amplitude, the electron is going nowhere. Remember, they travel straight up or down the wire in both AC and DC.
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