Four-terminal sensing
A constant current source sends a constant current to the resistor and its feed lines which is subject to analysis. With a high-impedance voltmeter the voltage at the resistor is measured. This voltage is directly proportional to the resistance value. Since the voltmeter is connected directly to the resistor and since there is almost no electric current in the feed lines (ideal voltmeter with infinitely high input resistance), electrical resistivity is compensated.
