How is the input current supplied in the Wenner Four-Pin Method?

In the Wenner Four-Pin Method, the input current is supplied from the two outside pins. This technique is utilized in electrical resistivity measurements of the ground. The setup involves four pins arranged in a straight line, where the outer pins serve as current electrodes that inject electrical current into the soil. The two inner pins function as potential electrodes, measuring the voltage drop caused by the current flowing through the soil.

This configuration is particularly effective because it helps ensure that the measurement of resistivity is not affected by the localized effects of the current injection and ensures a more uniform potential distribution in the measurement area. By using the outer pins for current supply, the Wenner method also minimizes the influence of contact resistance between the pins and the soil, leading to more accurate and reliable readings.

In essence, the design and functionality of the Wenner Four-Pin Method revolve around the principle that the outer pins are critical for supplying current, providing a clear and effective means of measuring soil resistivity.