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SESK: Stuff Everyone Should Know · sesk.info/ham-ohmmeter-how-it-works

How does an ohmmeter measure the resistance of a circuit or component?

It applies a small current and measures the resulting voltage.

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  1. It applies a small current and measures the voltage ✔
  2. It puts a variable resistor in series
  3. It reads resistance without applying any test signal

Why: The meter pushes a small current through the part and reads the voltage across it. Ohm's law turns those two numbers into resistance.

Huh, didn't know that: That's why an ohmmeter needs its own battery even though it tests unpowered parts.

The dad joke
Why was the ohmmeter so calm? It never let anything get past its resistance check.
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References

Answer: It applies a small current and measures the voltage. The meter pushes a small current through the part and reads the voltage across it. Ohm's law turns those two numbers into resistance.

  1. NCVEC 2026-2030 Technician Question Pool (February 19, 2026 errata) ncvec.org/downloads/2026-2030%20Technician%20Pool%20and%20Syllabus%20Public%20Release%20Feb%2019%202026.pdf
    A. By applying a small current and measuring the resulting voltage
    Checked 2026-10-09.

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