Which instrument is used to measure resistance in a circuit or component?

Which instrument is used to measure resistance in a circuit or component?

• A. Ohmmeters
• B. Ammeters
• C. Voltmeters
• D. Oscilloscopes

Answer: (A)

Measuring resistance is done by applying a known current and measuring the resulting voltage drop across a component, then using Ohm’s law to calculate resistance. An ohmmeter is designed for this job; it injects a small current from its internal source and measures the voltage to determine resistance (often as the ohm function on a digital multimeter). You should power the circuit off and, if possible, remove the component from the circuit, because power or parallel paths can give false readings. Ammeters measure current, voltmeters measure voltage, and oscilloscopes display voltage over time—these tools are used for different quantities, not for determining resistance.

Measuring resistance is done by applying a known current and measuring the resulting voltage drop across a component, then using Ohm’s law to calculate resistance. An ohmmeter is designed for this job; it injects a small current from its internal source and measures the voltage to determine resistance (often as the ohm function on a digital multimeter). You should power the circuit off and, if possible, remove the component from the circuit, because power or parallel paths can give false readings. Ammeters measure current, voltmeters measure voltage, and oscilloscopes display voltage over time—these tools are used for different quantities, not for determining resistance.