Extra exam question E5B07
Subelement E5, ELECTRICAL PRINCIPLES· Group E5B
What is the phase angle between the voltage across and the current through a series RLC circuit if XC is 500 ohms, R is 1 kilohm, and XL is 250 ohms?
- A.68.2 degrees with the voltage leading the current
- B.14.0 degrees with the voltage leading the current
- C.14.0 degrees with the voltage lagging the current (correct answer)
- D.68.2 degrees with the voltage lagging the current
WhyA series RLC circuit with XC of 500 ohms, R of 1 kilohm, and XL of 250 ohms has a phase angle of about 14.0 degrees, with the voltage lagging the current. With XC at 500 ohms and XL at 250 ohms, the net reactance is 250 minus 500, or negative 250 ohms, capacitive overall, and dividing that by the 1,000 ohm resistance and taking the arctangent gives a phase angle of about 14.0 degrees; since the net reactance is capacitive, the current leads the voltage, equivalently the voltage lags the current, answer C. The larger 68.2 degree figure and a voltage-leading description don't match this particular combination of reactances and resistance.
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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