Fundamental Circuit Analysis Flashcards

In node voltage analysis, the reference node is also called the:

Answer: Datum node — both B and D are correct

The reference node (ground) is also called the datum node; both terms are correct and used interchangeably.

What is the phase angle of the impedance in a circuit where R = 30 Ω and X_L = 40 Ω (purely inductive)?

Answer: 53.13°

θ = arctan(X_L/R) = arctan(40/30) = arctan(1.333) ≈ 53.13°.

Which of the following is a passive element that opposes a change in current?

Answer: Inductor

An inductor stores energy in a magnetic field and opposes changes in current through it (v = L di/dt).

A 120 V source has an internal resistance of 5 Ω. What is the maximum power that can be delivered to a load?

Answer: 720 W

At maximum power transfer (R_L = R_s = 5 Ω), P_max = V_s²/(4R_s) = 14400/20 = 720 W.

Which law states that the algebraic sum of all currents entering and leaving a node equals zero?

Answer: Kirchhoff's Current Law

KCL, based on charge conservation, states that the sum of currents at any node is zero.

In a purely capacitive AC circuit, the current:

Answer: Leads voltage by 90°

In a purely capacitive circuit, current leads voltage by 90° because i = C(dv/dt).

The Thevenin resistance R_th is found by:

Answer: Dividing V_th by I_N from the Norton equivalent

R_th = V_th / I_N, which can also be found by deactivating all independent sources and measuring resistance at the terminals.