Re: [Resistance Matrix] keyword

With regard to the units:

  It's Ohms.

With regard to the off-diagonal entries of the R-matrix:

  [R] really represents the voltages developed along the conductors in
response to DC current flows:

        V1 = R11 * I1 + R12 * I2
        V2 = R12 * I2 + R22 * I2

If R12 = 0, this is just saying that

        V1 = R11 * I1 and V2 = R22 * I2

and so the only voltage drop you get on the wire is due to current
flowing along THAT wire, and not the other one. This is like having
two separate wires with an ideal ground return:

              I2
             ---->
         V2 0---[ R22 ]---0 V2 - R22*I2

         I1
        ---->
    V1 0----[ R11 ] ---0 V1 - R11*I1
        + +
            - -
             0----------------0
              ground (ideal)
                     <---------
                       I1 + I2

Note that by KCL the current flowing back along the ground line is I1
+ I2; in this ideal case, there's no voltage developed due to the
ground current.

In the case where R12 is NONzero, this is like having a ground return
with some resistance Rg associated with it:

              I2
             ---->
         V2 0---[ R2 ]---0 V2 - R2*I2 - Rg*(I1 + I2)

         I1
        ---->
    V1 0----[ R1 ] ---0 V1 - R1*I1 - Rg*(I1 + I2)
        + +
            - -
             0----[ Rg ]----0
              ground (nonideal)
                     <---------
                       I1 + I2

Here, R12 = Rg and R11 = R1 + Rg, R22 = R2 + Rg.

I hope that this helps...

--Eric

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Received on Mon Apr 8 05:39:13 1996