SESKStuff Everyone Should Know
SESK: Stuff Everyone Should Know · sesk.info/ham-ohms-law-90v-3a

What is the resistance of a circuit where 3 amperes flows from 90 volts?

30 ohms, because resistance equals voltage divided by current.

  1. 30 ohms ✔
  2. 270 ohms
  3. 3 ohms

Why: Ohm's law says R = E / I. Divide 90 volts by 3 amps and you get 30 ohms. Multiplying instead gives 270, a common mistake.

Huh, didn't know that: Ohm's law is named for German physicist Georg Ohm, and E stands for electromotive force, another name for voltage.

The dad joke
Why did Ohm's dog never run away? It had too much resistance.
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Sources

  1. NCVEC 2026-2030 Technician Question Pool (Feb 19, 2026 release) https://www.ncvec.org/downloads/2026-2030%20Technician%20Pool%20and%20Syllabus%20Public%20Release%20Feb%2019%202026.pdf

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That's stuff everyone should know.