Govt. Exams
Entrance Exams
Since inductive reactance X_L = 2πfL and capacitive reactance X_C = 1/(2πfC), increasing frequency increases X_L and decreases X_C.
The slack bus serves as the reference point with fixed voltage magnitude and phase angle (typically 0°) in load flow studies.
XL = 2πfL = 2π(50)(5) = 500π ≈ 1570.8Ω. For pure inductor, impedance is purely reactive with magnitude 1570.8Ω.
H21 = I2/I1 (with V2=0) is the current transfer ratio or short-circuit current gain in a two-port network using hybrid parameters.
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.
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.
RTh is calculated by replacing independent voltage sources with short circuits and independent current sources with open circuits, while keeping dependent sources intact.
Both nodal and mesh analysis can handle dependent sources. The choice depends on circuit configuration - nodal for current sources, mesh for voltage sources.
A CCVS (Current-Controlled Voltage Source) depends on current through any element in the control branch, measured in the specified reference direction.
Z11 is defined as input impedance with port 2 open-circuited (I2=0). Therefore, Zin = Z11 only under this condition.
