What condition must be met before measuring resistance in a circuit?

Before measuring resistance in a circuit, it is essential that the circuit is powered off. This requirement is crucial for several reasons. First, measuring resistance with power applied can pose a safety hazard to the person using the multimeter, as it can lead to electric shock. Second, energized circuits can produce inaccurate readings on the multimeter because the presence of voltage can affect the resistance measurement.

Additionally, measuring resistance requires the multimeter to send a small current through the component being tested in order to determine how much opposition it provides to that current. If the circuit is powered on, the multimeter cannot properly measure resistance since the voltage already present in the circuit can interfere with the measurement process, resulting in misleading values.

In summary, turning off the power to the circuit ensures safety and provides accurate resistance readings, making it a vital step before proceeding with any resistance measurement.