With regards to soil resistivity test procedures, why does the distance between stakes should be the same with the depth of the electrode? for ex. if the depth of the electrode is 10ft., the space between stakes should be 10ft. also.
@samirehman2184
7 жыл бұрын
excellent ,excellent, its gives me really help,for the interview of assistant geophysicist in Pakistan. interview will be held in march,3 2017
@mivapusa
4 жыл бұрын
Great content, only the sound is so low that even with my audio near the safety limit, I struggle to hear
@chctham
2 жыл бұрын
Hi John, would like to ask one of my work. Current ground level is 11m above the soil layer i wish to find out on its soil resistivity. What spacing would you recommend? And how accurate it will be? I look at IEEE81, if it is 300%, the error can be reduce to low of +15% to -25% error.
@jombsgeoscientique8093
3 жыл бұрын
hi, i'm wondering how to determine the 'datum points'? are they 'fixed' pre-determined values? or is there a way to determine the datum points with respect to the method and configuration we are using? thank's in advance
@NickyG_vz
9 жыл бұрын
This is great material. Thanks for this
@hichamoueidat9308
8 жыл бұрын
great presentation sir. One question please. how can I know which array I should use during my test? thank you
@johnnlouie
8 жыл бұрын
I mostly use the Wenner array for both simple profiling and sounding. If I am trying to sound especially deep, I very occasionally use a Schlumberger array, since it does not requires the potential wires to be as long as for the Wenner. For true cross sections, you need a complete dipole-dipole survey.
@samirehman2184
7 жыл бұрын
u r my teacher, I became ur fan
@gatgongmajang950
3 жыл бұрын
it helped me a lot. thanks
@mahmoudnasser1316
7 жыл бұрын
preferd to use wenner array in profiling why ?
@johnnlouie
7 жыл бұрын
It's really just simplicity of deployment. Four electrodes, all with the same a-spacing between them.
@davefield8100
7 жыл бұрын
Question: What voltage is optimum for the current. 12V, 24V, etc. Also, does amperage matter? Is 20 amps better than 10 amps? Any input would be greatly appreciated.
@johnnlouie
7 жыл бұрын
We have a very nice little resistivity meter, an L&R Instruments MiniRes. This machine automatically steps up the voltage to the current electrodes, until it can achieve a measurable current between them through the ground. The voltage difference between the two current electrodes can reach several hundred volts, just to get a few milliamps flowing through the ground, if the site is very resistive. Such voltages are hazardous, so careful safety procedures are a necessity. No one handles any of the wires or connectors while measuring, and no one gets within one meter of the wires or probes until the MiniRes operator has disconnected them from the meter.
@davefield8100
7 жыл бұрын
Thanks John. That is the info I was looking for. I am aware of the safety issues when using those levels of voltage. Thanks again!!
@liquidcable
5 жыл бұрын
I think it's a ranges from 10's to hundreds
@zraidiayoub140
6 жыл бұрын
excellent thank you
@srm4258
3 жыл бұрын
Nice. I also suggest everyone interested in Resistivity and IP methods to check out the "electrical resistivity Tomography (ERT) - from zero to hero" playlist which goes through theory, software, etc. It is on ONE GEOSCIENTIST KZitem channel. Also check that.
@swayambhutripathi
8 жыл бұрын
Sir,i am stuck in few numerical problem related to resistivity survey...sir if you provide me your mail id i will mail you some problem..sir its my request to help me...because i am preparing for competitive exam from geophysics and some of the problems are quite hard Thank you sir,
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