Which of the following statements is not true about measuring the resistance of a component connected in a circuit?

Measuring the resistance of a component accurately requires that the power supply be turned off to ensure that no current is flowing through the component. If the power supply is on, the presence of voltage can interfere with the accuracy of the measurement, potentially leading to misleading readings. In fact, most ohmmeters, used for measuring resistance, cannot measure resistance in the presence of voltage, as they apply their own small voltage to determine resistance based on Ohm's law.

To measure resistance correctly, it is standard practice to connect the multimeter leads across the component. Consequently, the power supply must be turned off to prevent any conflicting signals. Additionally, disconnecting one lead of the component from the circuit ensures that the measurement reflects only that component's resistance and not any parallel pathways that could affect the reading.

Thus, keeping the power supply on while trying to measure resistance would compromise the integrity of the measurement process.