GEOS 3008 – Field Geology & Geophysics
Question and Answer Form – Self Potential
1. Observe the construction of the unusual electrodes, called “porous pots”.
What are the four individual components?
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Why is the outside of the ‘pot’ not glazed on the bottom?
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2. Place two ‘pots’ on a dry surface 2 m apart and connect them to the voltmeter.
What is the reading on the meter?
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3. Now wet the ground around the pots.
What is the reading on the meter?
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What is the implication of this for the use of pots on survey?
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4. Now reverse the positions of the two pots.
Is the reading different, and if so, in what way?
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What implication does this have for surveying?
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5. Continue to observe the reading.
Is it changing with time and if so, how?
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What is the reason for the change?
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What implication does this have for surveying?
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Tips for the Care and Operation of Porous Pots
1. Take care not to damage the pots, especially the ceramic shell which is
breakable.
2. Keep the outside, unglazed surface clean and free from dirt and mud.
3. Keep some undissolved crystals of the salt in the pots so as to ensure that
the solution is saturated.
4. When not in use, stand the pots in a dish containing the solution. The dish
should be non-metallic. Also connect the pots with a wire so as to “short” them. This
will prevent the build-up of potentials.