Electric Circuit Analysis Flashcards

Which theorem states that maximum power is transferred to a load when the load resistance equals the source's Thevenin resistance?

Answer: Maximum power transfer theorem

Maximum power transfer theorem states that PL is maximum when RL = Rth, yielding Pmax = Vth²/(4Rth).

A sinusoidal voltage v(t) = 170 sin(377t) V. What is its RMS value?

Answer: 120.2 V

VRMS = Vpeak/√2 = 170/√2 ≈ 120.2 V, which is the standard US household voltage.

In a parallel RLC circuit, resonance occurs when:

Answer: BL = BC (susceptances are equal)

In a parallel RLC circuit, resonance occurs when the inductive susceptance BL equals the capacitive susceptance BC, making the total susceptance zero.

KCL (Kirchhoff's Current Law) is based on conservation of:

Answer: Charge (current)

KCL states that the algebraic sum of currents at any node is zero, which is a consequence of conservation of charge.

The phase angle of impedance Z = 3 + j4 Ω is:

Answer: 53.13°

φ = arctan(X/R) = arctan(4/3) ≈ 53.13°, indicating the circuit is predominantly inductive.

In a source transformation, a voltage source VS in series with RS is equivalent to a current source of:

Answer: IS = VS/RS in parallel with RS

A voltage source VS in series with RS transforms to a current source IS = VS/RS in parallel with RS.

For a first-order RC circuit with time constant τ = RC, the voltage across the capacitor after 2τ seconds (starting from 0 V, charging to V0) is approximately:

Answer: 86.5% of V0

VC(t) = V0(1 − e^(−t/τ)); at t = 2τ, VC = V0(1 − e⁻²) ≈ V0 × 0.865 = 86.5% of V0.