Technician exam question T5A08
Subelement T5, ELECTRICAL PRINCIPLES· Group T5A
T5A08
Which of the following is a good electrical insulator?
- A.Sea water
- B.Glass (correct answer)
- C.Stainless steel
- D.Graphite
WhyGlass is a good electrical insulator. Glass has essentially no free electrons available to carry current, making it a good electrical insulator, answer B. Sea water (A), stainless steel (C), and graphite (D) all conduct electricity reasonably well, sea water through dissolved ions, and steel and graphite through free electrons, so none of them is an insulator.
Published 2026-08-28 · Last updated 2026-08-28 · Question text is verbatim from the 2026-2030 NCVEC Element 2 pool (public domain); the explanation above is original writing, see our methodology.
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