AC Circuits and Analysis Flashcards
7 cards from real ISCET practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 AC Circuits and Analysis flashcards as text
In a series RLC circuit at resonance, what happens to the impedance?
Answer: Impedance equals the resistance R
At resonance, XL and XC cancel, leaving only the resistive component R as the total impedance.
What is the phase angle between voltage and current in a purely capacitive AC circuit?
Answer: Current leads voltage by 90°
In a purely capacitive circuit, current leads the voltage by 90 degrees.
If the frequency of an AC signal doubles, what happens to the capacitive reactance (XC)?
Answer: XC halves
Since XC = 1/(2πfC), doubling frequency halves the capacitive reactance.
The power factor of an AC circuit is defined as:
Answer: True power divided by apparent power
Power factor equals true (real) power divided by apparent power, or equivalently cos(θ).
A transformer has a primary winding of 200 turns and a secondary winding of 50 turns. If 120V AC is applied to the primary, what is the secondary voltage?
Answer: 30V
Using the turns ratio: Vs = Vp × (Ns/Np) = 120 × (50/200) = 30V.
In an AC circuit, reactive power is measured in:
Answer: Volt-amperes reactive (VAR)
Reactive power, which represents energy stored and returned by reactive components, is measured in volt-amperes reactive (VAR).
What is the resonant frequency of a series LC circuit with L = 10 mH and C = 10 µF?
Answer: approximately 503 Hz
fr = 1/(2π√LC) = 1/(2π√(0.01 × 0.00001)) ≈ 503 Hz.