HAM FREE HAM Radio Extra Class Test Advanced Electrical Principles Questions and Answers 2 — Questions and Answers
Question 1: What is the resonant frequency of a series RLC circuit with an inductance of 10 microhenries and a capacitance of 100 picofarads?
- 5.03 MHz (Correct answer)
- 10.1 MHz
- 15.9 MHz
- 1.59 MHz
Correct answer: 5.03 MHz
Using f = 1/(2π√(LC)), with L = 10 µH and C = 100 pF, the resonant frequency calculates to approximately 5.03 MHz.
Question 2: In a circuit operating at 14 MHz, what is the reactance of a 300 picofarad capacitor?
- 37.9 ohms (Correct answer)
- 75.8 ohms
- 18.9 ohms
- 151.6 ohms
Correct answer: 37.9 ohms
Capacitive reactance Xc = 1/(2πfC) = 1/(2π × 14×10⁶ × 300×10⁻¹²) ≈ 37.9 ohms.
Question 3: What happens to the impedance of a parallel resonant circuit at the resonant frequency?
- Impedance reaches its maximum value (Correct answer)
- Impedance reaches its minimum value
- Impedance equals zero
- Impedance becomes purely capacitive
Correct answer: Impedance reaches its maximum value
At resonance, a parallel RLC circuit exhibits maximum impedance because the inductive and capacitive branch currents cancel each other.
Question 4: What is the skin effect in a conductor at RF frequencies?
- Current tends to flow near the surface of the conductor (Correct answer)
- Current flows uniformly through the conductor cross-section
- Current flows only through the center of the conductor
- Current reverses direction at the conductor surface
Correct answer: Current tends to flow near the surface of the conductor
At RF frequencies, alternating current concentrates near the outer surface of a conductor due to electromagnetic induction, increasing effective resistance.
Question 5: What is the power factor of a circuit with a phase angle of 45 degrees between voltage and current?
- 0.707 (Correct answer)
- 0.500
- 0.866
- 1.000
Correct answer: 0.707
Power factor equals the cosine of the phase angle, so cos(45°) = 0.707.
Question 6: What is the Q factor of a series RLC circuit with a resistance of 5 ohms, an inductance of 10 microhenries at a resonant frequency of 7.1 MHz?
- 89.2 (Correct answer)
- 44.6
- 178.4
- 22.3
Correct answer: 89.2
Q = (2πfL)/R = (2π × 7.1×10⁶ × 10×10⁻⁶)/5 ≈ 89.2.
HAM FREE HAM Radio Extra Class Test Advanced Electrical Principles Questions and Answers 2
What is the resonant frequency of a series RLC circuit with an inductance of 10 microhenries and a capacitance of 100 picofarads?