Mostafa Ebrahimi,

When you ask questions like this, spell out what all the acronyms. IP is mostly "intellectual property" or other things on the Internet.

"electrical resistivity tomography" "induced polarization" gives 42,100 entries on Google search. That means it is fairly mature.

It shows up on Wikipedia immediately, as

https://en.wikipedia.org/wiki/Induced_polarization

https://en.wikipedia.org/wiki/Geophysical_imaging

https://en.wikipedia.org/wiki/Spectral_induced_polarisation

https://en.wikipedia.org/wiki/Electrical_impedance_tomography (related)

You need to search for specific instruments. They can often explain the methods clearly and simply.

https://www.guidelinegeo.com/resistivity-and-induced-polarization/

I was just looking at "earth conductivity models" today. Resistivity is somewhat out of vogue now, so try searching for "conductivity".

The simplest thing to do is search for

"induced polarization" "amperes" which has 12,900 entry points

Just reading the summaries it looks like 2 to 10 amperes is common.

Also look into "magnetotelluric", "acoustic magnetotelluric"

When you ask questions, also say why you want to know, what you have already tried, and why it is important.

Many electromagnetic and gravitational imaging methods use passive sources - lightning, cosmic ray magnetic impulses, ionospheric storms, solar magnetic storms, human generated signals of many sorts. If they have low frequencies or operate for long periods, part of the signal can go through the earth and then be used for imaging.

Richard Collins, Director, The Internet Foundation

Richard Collins , There is a word count limitation in the question section. So, despite spelling out this geophysical terminology in the description, I was unable to spell out the IP word in the question. I also believe the experts who are working in this field area are familiar with the ERT and IP terminology, and what the IP word stands for.

What were you trying to do? It is a fairly mature topic and much written about it. In these message boxes, you can write as much as you want. So if you are still trying to get answers, or want to work with others, you can write it out and hope more words will attract discussion to fill in gaps or areas of your interest.

Perhaps ResearchGate needs to re-think the tools and methods for questions. I am happy to help when I have time, but I cannot read minds. Questions only show up on my side bar that are fairly close to my interests.

I cover the whole Internet and all human knowledge in my Internet reviews. There is almost no acronym that does not get re-used and often mis-used. Thanks for explaining the limitations that ResearchGate put on people trying to meet and communicate. I get tired of having to check to see what people are most likely to have meant. Guessing motivation and intent and purposes.

Did you find your answer yourself? If so, perhaps, since these questions never seem to disappear - you might write out what you found. The Internet does not work like the real world. It is not quite a permanent and self-organizing memory of the human species. It could be, but probably not in my lifetime.

I don't found yet about the minimum electrical current in resistivity or/ and IP method that is written on the scientific paper. But, in my experience, the electrical current that is considered to be good is depending on the resistance of earth surface. Sometimes, the minimum current of 10 mA will still give the good response of potential value. I think if the equipment has the minimum output current of 100 mA, it can be used every where although the earth surface has a high resistance.

well,

let me be straightforward,

for ERT:

1- there are no standard values (minimum or maximum) for the injected electrical current.

2- It depends on the investigated depth, the deeper the higher value of the electrical current is needed because the current will be distributed over a larger volume of the ground. In another word, it is related to the length of the array and the distance between the poles.

3- Usually, the injected current should be increased with a deeper level of investigation "n". For example,

with n1 use 0.1 mA

with n2 use 0.1 mA

with n3 use 0.2 mA

with n4 use 0.2 mA

with n5 use 0.3 mA

4- It depends on the conductivity of the studied site, for example;

a- with clayey and moist soil, small values of the injected current might be enough,

b- with sandy and dry soil, higher values might be better.

Hello Dear Mostafa,

In my experiences, it is a variable component that according your instrument, the desired depth of exploration, instrument used and earth conductivity could have different values. For example, in schlumberger array , in a filed; we use lower current in closer AB and as the current electrodes move away, we also increase the amount of current.

Yes, there are several scientific papers and documents that discuss the typical input currents used in Electrical Resistivity Tomography (ERT) and Induced Polarization (IP) surveys. Here are some examples:

It is important to note that the optimal input current for ERT and IP surveys will depend on several factors, including the subsurface conditions, the electrode configuration, and the desired depth of investigation. It is always recommended to consult with an experienced geophysicist or follow established standards and guidelines when conducting ERT and IP surveys.