When measuring resistance with an ohmmeter, what must you do with the part being measured?

When measuring resistance with an ohmmeter, the part being measured must be isolated from the rest of the circuit. This isolation is crucial because if the component remains connected to a circuit, other pathways or components might affect the resistance reading, potentially giving false or misleading results.

When a component is disconnected, the ohmmeter can accurately determine the resistance by applying a voltage across the terminals of the component and measuring the resulting current flow. This setup ensures that only the resistance of the specific part being tested is measured, free from any interference from other components or circuit paths.

Using an ohmmeter in any other manner, such as keeping the component connected to the circuit, could result in erroneous readings. Components connected to a power source, or measuring resistance under load, further complicates the measurement and can lead to both inaccurate readings and potential damage to the multimeter or the component itself. By isolating the part, the test results are valid and meaningful.