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

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

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

Answer: (B)

To measure resistance directly, you need an instrument that applies a small source of energy to the component and measures the resulting current or voltage to compute R. An ohmmeter does exactly that—its internal source pushes current through the component and the instrument reads the voltage drop (or vice versa) to calculate resistance using Ohm’s law. That specialization is what makes it the instrument designed for resistance measurement, and in many digital meters you’ll find an ohms setting specifically for this purpose. Voltmeteres measure voltage, not resistance. They read the potential difference across two points. Ammeters measure current, reading how much current flows through a component and are placed in series. Oscilloscopes display voltage vs. time and can reveal waveform characteristics; while you could infer resistance by combining voltage and current measurements, an oscilloscope isn’t meant for direct resistance measurement. Note that for accurate resistance readings, the circuit should be de-energized and the component isolated, since power and parallel paths in a live circuit can distort the result.

To measure resistance directly, you need an instrument that applies a small source of energy to the component and measures the resulting current or voltage to compute R. An ohmmeter does exactly that—its internal source pushes current through the component and the instrument reads the voltage drop (or vice versa) to calculate resistance using Ohm’s law. That specialization is what makes it the instrument designed for resistance measurement, and in many digital meters you’ll find an ohms setting specifically for this purpose.

Voltmeteres measure voltage, not resistance. They read the potential difference across two points. Ammeters measure current, reading how much current flows through a component and are placed in series. Oscilloscopes display voltage vs. time and can reveal waveform characteristics; while you could infer resistance by combining voltage and current measurements, an oscilloscope isn’t meant for direct resistance measurement.

Note that for accurate resistance readings, the circuit should be de-energized and the component isolated, since power and parallel paths in a live circuit can distort the result.