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Earth, Planets and Space
Fig. 4 | Earth, Planets and Space

Fig. 4

From: A procedure for stable electrical measurements on a rock sample against high contact resistance as a prerequisite for electrical tomography

Fig. 4

Measurement scheme. z and θ are coordinates defined in Fig. 2a. The dotted square is a resistance meter, RIN is input resistance, RV is insulation resistance between the negative terminal and chassis ground, HI labels positive terminals, LO labels negative terminals, C1 and C2 are current electrodes, and P1 and P2 are potential electrodes. The electrometer (Model 6514, Keithley, Cleveland, Ohio, US.) in resistance measurement mode injects known direct constant current, measures the voltage caused by injected current, and obtains resistance. An ammeter (Model 3458A, Keysight; Santa Rosa, California, USA) was placed in order to monitor the amount of injected current. Electrometers (Model 6514, Keithley, Cleveland, Ohio, US.) with RIN = 200 TΩ acted as the resistance meter and the voltmeter

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