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. If you are actively surveying a large region you might use higher power levels. It depends on the character of the earth or materials where you are trying to look.
It shows up on Wikipedia immediately, as
You need to search for specific instruments. They can often explain the methods clearly and simply.
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