General exam question G5B01
Subelement G5, ELECTRICAL PRINCIPLES· Group G5B
G5B01
What dB change represents a factor of two increase or decrease in power?
- A.Approximately 2 dB
- B.Approximately 3 dB (correct answer)
- C.Approximately 6 dB
- D.Approximately 9 dB
WhyA change of approximately 3 dB represents a factor of two increase or decrease in power. Doubling or halving power corresponds to a change of about 3 dB, since dB = 10 log10(P2/P1) and 10 log10(2) is approximately 3, answer B. The other values correspond to different power ratios (roughly 1.6x for 2 dB, 4x for 6 dB, and 8x for 9 dB), not a factor of two.
Published 2026-08-28 · Last updated 2026-08-28 · Question text is verbatim from the 2023-2027 NCVEC Element 3 pool (public domain); the explanation above is original writing, see our methodology.
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