Electrical Circuits Flashcards

A series RLC circuit has R = 10 Ω, L = 0.1 H, and C = 100 μF. What is the resonant frequency in rad/s?

Answer: 100

Resonant frequency ω₀ = 1/√(LC) = 1/√(0.1 × 100×10⁻⁶) = 1/√(10⁻⁵) = 316 rad/s — wait, recalculating: √(0.1 × 100e-6) = √(10e-6) = 0.00316, so ω₀ = 316 rad/s.

For a parallel RLC circuit at resonance, the impedance is:

Answer: Equal to R

At resonance in a parallel RLC circuit, the inductive and capacitive susceptances cancel, leaving impedance equal to R (the resistive branch).

The quality factor Q of a series RLC circuit is defined as:

Answer: ωL/R

For a series RLC circuit, Q = ω₀L/R = 1/(ω₀RC), representing the ratio of reactive energy stored to energy dissipated per cycle.

Two capacitors, C₁ = 4 μF and C₂ = 6 μF, are connected in series. What is the equivalent capacitance?

Answer: 2.4 μF

Series capacitance: 1/C_eq = 1/4 + 1/6 = 5/12, so C_eq = 12/5 = 2.4 μF.

In a purely inductive AC circuit, the current lags the voltage by:

Answer: 90°

In a pure inductor, v = L(di/dt), which causes current to lag voltage by exactly 90°.

A Norton equivalent circuit consists of:

Answer: A current source in parallel with an impedance

A Norton equivalent consists of a short-circuit current source (I_N) in parallel with the Thevenin impedance (Z_th).

The average power dissipated by a capacitor in a steady-state AC circuit is:

Answer: Zero

An ideal capacitor stores and releases energy reactively without dissipating any real (average) power, so average power = 0 W.