Re: [Phys-l] Need advice to built earth resistivity meter

[Bernard Cleyet <bernardcleyet@redshift.com>]

Unless the separation is great and / or deeply buried, I don't think 
water detection at 1500 feet is likely.  Harnwell gives the formula for 
hemispheres buried, as a function of their radii and separation, in a 
homogeneous, semi-infinite, and flat earth. 

Googling:   measuring earth resistance

results in many articles in answer to your question.

While:  measuring earth resistance water

is more specific.


bc, only glanced at several, but, as a result, should modify his claim.

p.s W/ out having read carefully, I suspect an AC P/S w/ synchronous 
detection "is the way to go".

Roberto Carabajal wrote:

> > Hello Friends:
> >
> > One studient have the idea of built an earth resistivity meter capable of
> > sounding very deeply, for example, used to detect water at 1500 feets. The
> > problem involves metering of very low current values with good  accuracy,
> > and good knowledge of earth current distribution density laws. 
> > It is an interesting problem but we need help finding circuits that can be
> > used in this project,  especially because the idea is to use standard
> > commercial equipment (low  cost digital meters and common batterys).
> > Perhaps somebody have seen such experimental equipment. Any help would be
> > appreciated. 
> >
> > My best regards.
> > Roberto
> >    
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