Instrument capability clarification: Evaluate the statement: “A digital voltmeter can be used to measure resistance.” (Assume a device marketed strictly as a digital voltmeter.)

Difficulty: Easy

Correct Answer: Incorrect

Explanation:

Introduction / Context:Test instruments are often named for their primary function, and that name matters. A digital voltmeter measures voltage, whereas a digital multimeter (DMM) measures multiple quantities such as voltage, current, and resistance. Understanding the distinction prevents misuse and incorrect expectations in the lab.

Given Data / Assumptions:

  • The instrument in question is a digital voltmeter (DVM), not a multimeter.
  • The statement claims resistance measurement capability for a DVM.
  • We assume no add-on fixtures or external sources are used.

Concept / Approach:Measuring resistance requires injecting a known current through the unknown resistor and measuring the resulting voltage (or applying a known voltage and measuring current). A DMM provides an internal source and measurement path for this; a DVM typically does not. Therefore, a dedicated DVM lacks the native circuitry to perform ohmic measurements unless it includes a resistance function, in which case it is by definition a multimeter or a specialized ohmmeter—not a pure voltmeter.

Step-by-Step Solution:

Define instrument scope: DVM = voltage only.Define requirement for resistance: needs internal source and computation R = V/I.Note absence of source path in a pure DVM.Conclude that the statement is incorrect unless the device is actually a DMM.

Verification / Alternative check:Product datasheets label meters with resistance ranges (Ω) as multimeters. Pure voltmeters list DCV/ACV ranges only—no Ω function present—confirming the functional distinction.

Why Other Options Are Wrong:

  • Correct: Would only be true if the device were a multimeter, not a dedicated voltmeter.
  • External current source: With elaborate setups a DVM can participate, but that is not what the statement implies.
  • Only above 10 kΩ / analog meters only: These are unrelated and inaccurate limitations.

Common Pitfalls:Using “DVM” as a generic synonym for DMM; assuming any digital meter can measure all quantities. Always check the meter’s front panel and specifications.

Final Answer:Incorrect

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