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SESK: Stuff Everyone Should Know · sesk.info/ham-glass-insulator

Which of these is a good electrical insulator?

Glass does not let current flow easily.

  1. Sea water
  2. Glass ✔
  3. Graphite

Why: Insulators block the flow of current because their electrons are held tightly. Glass is a classic insulator. Salt water and graphite both conduct electricity.

Huh, didn't know that: Old glass insulators from telegraph and power poles are now popular collectibles.

The dad joke
Why did the glass insulator never get any gossip? Nothing ever got through to it.
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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

Test yourself in the game

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That's stuff everyone should know.