Extra exam question E5B04
Subelement E5, ELECTRICAL PRINCIPLES· Group E5B
What is the time constant of a circuit having two 220-microfarad capacitors and two 1-megohm resistors, all in parallel?
- A.55 seconds
- B.110 seconds
- C.440 seconds
- D.220 seconds (correct answer)
WhyA circuit with two 220-microfarad capacitors and two 1-megohm resistors, all in parallel, has a time constant of 220 seconds. Two 220 microfarad capacitors in parallel combine to 440 microfarads total, and two 1 megohm resistors in parallel combine to 500 kilohms total, so the time constant, resistance times capacitance, works out to 500,000 ohms times 0.00044 farads, or 220 seconds, answer D. Using the individual component values instead of the correctly combined parallel totals, or combining them incorrectly, produces the other listed figures.
Published 2026-08-28 · Last updated 2026-08-28 · Question text is verbatim from the 2024-2028 NCVEC Element 4 pool (public domain); the explanation above is original writing, see our methodology.
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