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The 4-wire ohms method provides the most accurate way to measure small resistances because it reduces test lead and contact resistances. This is often used in automated test applications where resistive and/or long cable, numerous connections, or switches exist between the multimeter and the DUT.

Resistance is measured with the circuit's power turned off. The ohmmeter sends its own current through the unknown resistance and then measures that current to provide a resistance value readout.

Resistance measurement procedures Turn off the power to the circuit. ... Plug the test probes into the appropriate probe jacks. ... Select the ohms function by turning the function switch to ohms. ... Touch the probes together to check the leads, connections, and battery life.

Due to its unique properties, the quantum Hall resistance has become the primary standard of resistance metrology worldwide. For practical reasons, the quantum Hall resistance usually is used at i = 2.

Resistance standards traceable to NIST provide references for measurements of current at levels from 3000 A to below 20 fA and are used to support a wide variety of impedance, temperature, strain, and power measurements.

For most applications you can use a basic Ohm's Law equation of I = V/R where I is the current through the conductor (given in amperes), V is the potential difference measured across the conductor (given in volts), and R is the resistance of the conductor (here R is a constant given in ohms).

Overview. NIST works to improve the accuracy of measurements, enhance consumer protection, foster fair competition, and facilitate economic growth and trade through technical activities that promote uniformity in national and international legal metrology laws, regulations, standards, test procedures and enforcement.

Two primary methods for measuring resistance are the ammeter/voltmeter and the specialized megohmmeter approach. The ammeter/voltmeter approach calculates resistance by measuring voltage and current across a resistor, but circuit connections may affect its accuracy.

Ohmmeter Measurement Procedures Verify that all power is OFF to the circuit and remove the component being tested from the circuit. Set the ohmmeter function switch to the resistance mode as required. ... Plug the black test lead into the common jack when required.