Final answer:
An ohmmeter should never be connected to a live circuit with current running through it as it can be damaged. Instead, to measure resistance accurately, the component must be isolated from the circuit, with no power source or current involved.
Step-by-step explanation:
The statement "An ohmmeter must be connected to a live circuit" is false. An ohmmeter is used to measure the resistance of a component and must not be connected to a circuit that is "live", meaning a circuit that has a voltage source connected with the current flowing through it. Connecting an ohmmeter to a live circuit can lead to damage to the meter.
When using an ohmmeter, the component of interest should be isolated from the rest of the circuit. This isolation ensures that the measurement reflects the resistance of the component alone, not the equivalent resistance of the entire circuit. For accurate measurements, the component should have all power removed, and any stored energy should be discharged before the resistance measurement is conducted.
Standard voltmeters and ammeters may alter the circuit they are connected to, affecting their accuracy. Ammeters are designed to measure current and are therefore placed in series with the circuit element, while voltmeters are used to measure voltage and must be connected in parallel. When measuring resistance with an ohmmeter, Ohm's Law (R = V/I) is applied, where the internal battery provides the voltage (V) and the current (I) is measured by the meter through the component. In this way, the resistance is determined.