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What type of array is depicted in A?
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What type of array is depicted in B?
- Current and voltage (after SP removal) were measured to be 100 milliamps and 1 Volt in both of the two arrays shown.
(answers)
- What was the apparent resistivity for these measurements in A?
- What was the apparent resistivity for these measurements in B?
- Explore the voltage that will be recorded by these two arrays:
- Use a spreadsheet to build a graph of voltage as a function of electrode spacing, assuming the source current is 1 amp, and the ground is a uniform halfspace with resistivity of 10 Ohm-m.
- For each array, at what spacing will the signal drop below noise level if the instrument has a sensitivity of 1 millivolt?
- Which array will be preferable if it looks like signals will be weak?
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Of all the 8 array configurations (illustrated here), which will provide the strongest voltage measurements for any given source current and "a" spacing?
- For any given electrode spacing, will very resistive or very conductive ground result in voltages that will be rather small?
- For the same instrument as described in question 4, what ground resistivity would result in unmeasurably small voltages if the "a" spacing was 50 metres?
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