Which instrument can measure voltage, current, and resistance depending on the mode?

• A. Multimeter
• B. Ammeter
• C. Voltmeter
• D. Ohmmeter

Answer: (A)

A multimeter is the instrument used because it handles several measurements in one tool, just by changing its mode. In voltage mode, you place the probes across a component or power source to read voltage (AC or DC, depending on the meter). In current mode, you insert the meter in series with the circuit so it can measure the flow of electrons through it, using the appropriate current range. In resistance mode, you power the circuit off and connect the probes to the component so the meter can apply a small internal current and measure the response to determine resistance. This versatility is what makes the multimeter capable of measuring voltage, current, and resistance, whereas the other instruments specialize in only one quantity.