I'm not sure of the proper term here, but I'd guess it is either earth, ground or grounding resistance.(adsbygoogle = window.adsbygoogle || []).push({});

The task is to compute this grounding resistance for a sphere electrode (radius a) in a ground (conductivity sigma). The definition given for grounding resistance "between the surface of the electrode and a distant point in the ground" is the ratio ofvoltage between these two points(let say a and b) andcurrent to the electrode, U_ab / I.

But I don't really know how I should use the definition in this computation. All I can come up with is this:

sigma = 1/rho => rho = 1/sigma

[tex]\Large R=\frac{\rho L}{A},L=dr,A=2 \pi r^2[/tex]

[tex]\Large dR = \frac {\rho dr} {2 \pi r^2}[/tex]

[tex]\Large R=\int_a^b dR[/tex]

But this gives the resistance of the whole sphere of ground, right?

So should I just compute using the first equation, where L=distance between a and b, A=pi*a^2 (cross section of an imaginary tube just big enough to swallow the electrode)? Doesn't make sense either.

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# Homework Help: Grounding resistance

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