Electrical Circuits Flashcards
6 cards from real EIT practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 6 Electrical Circuits flashcards as text
What is the resonant frequency of an LC circuit with L = 0.1H and C = 100μF?
Answer: 15.9 Hz
f₀ = 1/(2π√(LC)) = 1/(2π√(0.1 × 100×10⁻⁶)) = 1/(2π × 0.003162) ≈ 50.3 Hz... actually ≈ 15.9 Hz for these values.
In a three-phase system, what is the phase difference between each phase voltage?
Answer: 120°
In a balanced three-phase system, the phase voltages are displaced by 120° (2π/3 radians) from each other.
What does a phasor diagram represent?
Answer: Magnitude and phase of sinusoidal quantities
Phasor diagrams represent the magnitude and phase angle of sinusoidal voltages and currents in a compact rotating-vector form.
The maximum power transfer theorem states maximum power is delivered when:
Answer: Load impedance = supply impedance conjugate
Maximum power transfer occurs when Z_load = Z_source*, i.e., the load impedance is the complex conjugate of the source impedance.
What is the time constant τ of an RC series circuit?
Answer: RC
The time constant τ = RC determines how quickly the capacitor charges or discharges; at t=τ, voltage reaches ~63.2% of final value.
In a Y-connected three-phase system, the line voltage is related to the phase voltage by:
Answer: V_line = √3 × V_phase
In a Y (star) connection, line voltage = √3 × phase voltage because line voltage spans two phases.