USCG Exam PracticeDC circuits and electronic principles
A series RLC circuit has R = 5 Ω, inductive reactance XL = 20 Ω, and capacitive reactance XC = 16 Ω at the operating frequency. What is the impedance of the circuit?
- A. 5 Ω
- B. √(5² + 36²) ≈ 36.3 Ω
- ✓ √(5² + 4²) ≈ 6.4 ΩCorrect
- D. √(5² + 20²) ≈ 20.6 Ω
Why C is correct
Net reactance X = XL − XC = 20 − 16 = 4 Ω. Impedance Z = √(R² + X²) = √(25 + 16) = √41 ≈ 6.4 Ω. XL and XC partially cancel; only the net reactance combines vectorially with R. Option D incorrectly uses XL alone, ignoring XC. (NEETS Mod. 2 §4-1)
Cited:NEETS Mod. 2 §4-1