The superposition theorem can be applied to find which of the following in a circuit?
Answer: B
Superposition theorem applies to linear networks and can be used to find voltage and current, but NOT power (since power is non-linear function).
Q.82Easy
In a planar circuit with B branches, N nodes, and L independent loops, the relationship between them is given by:
Answer: A
This is Euler's formula for planar networks: Number of independent loops (L) = Number of branches (B) - Number of nodes (N) + 1. This is fundamental in mesh analysis.
Q.83Medium
For a two-port network, if Z-parameters are known, the relationship between input impedance and Z11 is:
Answer: C
Z11 is defined as input impedance with port 2 open-circuited (I2=0). Therefore, Zin = Z11 only under this condition.
Q.84Medium
In a circuit with a dependent voltage source controlled by current, the controlling current flows through:
Answer: C
A CCVS (Current-Controlled Voltage Source) depends on current through any element in the control branch, measured in the specified reference direction.
Q.85Medium
Which method is most suitable for analyzing a circuit containing multiple independent and dependent sources?
Answer: C
Both nodal and mesh analysis can handle dependent sources. The choice depends on circuit configuration - nodal for current sources, mesh for voltage sources.
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Q.86Medium
The Thevenin equivalent resistance (RTh) of a network is found by:
Answer: D
RTh is calculated by replacing independent voltage sources with short circuits and independent current sources with open circuits, while keeping dependent sources intact.
Q.87Easy
In mesh analysis, for a circuit with 'm' meshes, the number of independent mesh equations is:
Answer: A
Number of independent mesh equations equals the number of independent loops (meshes) in the circuit. For m meshes, we need exactly m independent KVL equations.
Q.88Medium
A network is reciprocal if the transfer impedance Z12 equals Z21. This property holds for networks containing:
Answer: B
Reciprocity theorem applies to linear passive networks without dependent sources. If Z12 = Z21, then a voltage at port 1 producing current at port 2 equals the reverse situation.
Q.89Medium
In a circuit with time-varying sources, Kirchhoff's current law states that the algebraic sum of currents at a node is:
Answer: C
KCL is based on charge conservation and applies at ALL times - steady state and transients both. It's independent of whether sources are constant or time-varying.
Q.90Medium
For a two-port network with H-parameters (hybrid parameters), H21 represents:
Answer: B
H21 = I2/I1 (with V2=0) is the current transfer ratio or short-circuit current gain in a two-port network using hybrid parameters.
Q.91Hard
In a circuit with mutual inductance M between two coils, if the coupling coefficient k = 0.8, L1 = 10H, then L2 is at least:
Answer: A
Coupling coefficient k = M/√(L1·L2). For k=0.8 and L1=10H: 0.8 = M/√(10·L2). Since M ≤ √(L1·L2), we get L2 ≥ (M/k)²/L1 = (10·k²)/k² = L1/k² = 010.64 = 15.625H minimum requires M evaluation, but using k = M/√(L1L2) ≤ 1 gives L2 ≥ 6.25H.
Q.92Hard
A circuit has a loop containing 5V source, 10V source (opposite polarity), 2Ω, and 3Ω resistors. Using KVL, the current magnitude in the loop is:
Answer: A
Applying KVL around loop: 5 - 10 + 2I + 3I = 0 (taking voltages in one direction). This gives -5 + 5I = 0, so I = 1A.
Q.93Hard
In ABCD parameters of a two-port network, parameter C represents:
Answer: B
In ABCD parameters: V1 = AV2 - BI2; I1 = CV2 - DI2. C = I1/V2 (with I2=0) is the forward transadmittance with dimensions of admittance (Siemens).
Q.94Medium
For a circuit under steady-state AC conditions, the impedance of a 5H inductor at 50Hz frequency is approximately:
Answer: A
XL = 2πfL = 2π(50)(5) = 500π ≈ 1570.8Ω. For pure inductor, impedance is purely reactive with magnitude 1570.8Ω.
Q.95Easy
In a linear circuit with three independent loops, the number of independent mesh equations required for complete analysis is:
Answer: A
For a circuit with m independent loops (meshes), exactly m independent mesh equations are required. Each mesh contributes one independent equation. Therefore, for 3 loops, 3 equations are needed.
Q.96Easy
What is the primary function of a transformer in a power system?
Answer: A
Transformers step up voltage for transmission (reducing current and losses) and step down voltage for distribution to consumers.
Q.97Easy
The per unit system in power system analysis is based on:
Answer: B
Per unit system uses selected base values for voltage, power, and impedance to normalize calculations across different system parts.
Q.98Easy
Which of the following represents the power factor in a three-phase AC circuit?
Answer: A
Power factor is defined as cos(φ), the cosine of the phase angle between voltage and current waveforms.
Q.99Medium
In load flow analysis, which bus is used to represent the reference point for voltage angle?
Answer: C
The slack bus serves as the reference point with fixed voltage magnitude and phase angle (typically 0°) in load flow studies.
Q.100Medium
What is the effect of increasing system frequency above nominal value in a power system?
Answer: C
Since inductive reactance X_L = 2πfL and capacitive reactance X_C = 1/(2πfC), increasing frequency increases X_L and decreases X_C.
