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UPSC ESE E&T Network Theory Syllabus
Every chapter and topic of Network Theory examined in UPSC ESE E&T — 3 chapters, 11 topics, plus 51 flashcards written against it.
Network Theory syllabus — full chapter and topic list
Expand any chapter to see its topics and sub-topics. This is the whole examinable outline for Network Theory in UPSC ESE E&T, not a summary of it.
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Network Theorems
4 topics- Superposition Theorem
- Thevenin's Theorem
- Norton's Theorem
- Maximum Power Transfer Theorem
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Transient and Steady-State Analysis
3 topics- RC, RL, and RLC Circuits
- Laplace Transform
- Fourier Series and Transform
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Two-Port Networks
4 topics- Z-Parameters
- Y-Parameters
- H-Parameters
- Transmission Parameters
Network Theory flashcards for UPSC ESE E&T
25 of 51 cards from the Network Theory deck — real questions with worked answers.
State the Superposition Theorem.
In a linear circuit with multiple independent sources, the response (voltage or current) in any element equals the algebraic sum of the responses caused by each independent source acting alone, with all other independent sources deactivated (voltage sources short-circuited, current sources open-circuited).
When deactivating sources to apply Superposition, how do you treat ideal voltage and current sources?
Replace each ideal voltage source by a short circuit and each ideal current source by an open circuit; internal impedances of practical sources are retained.
Why can't the Superposition Theorem be used to directly calculate power in a resistor?
Power is a nonlinear (square-law) function of voltage/current (P = I²R), and superposition applies only to linear quantities. Currents/voltages must first be summed, then power computed from the total.
To which class of circuits does the Superposition Theorem apply?
Only to linear, bilateral circuits (elements obeying linearity and the principles of homogeneity and additivity); it does not apply to nonlinear circuits.
State Thevenin's Theorem.
Any linear two-terminal network can be replaced by an equivalent circuit consisting of a single voltage source Vth (the open-circuit voltage at the terminals) in series with a single resistance/impedance Rth (Zth) measured at the terminals with all independent sources deactivated.
How is the Thevenin voltage Vth determined?
Vth is the open-circuit voltage measured across the two output terminals after removing the load.
How is Thevenin resistance Rth found when a network contains only independent sources?
Deactivate all independent sources (short voltage sources, open current sources) and compute the equivalent resistance looking back into the two terminals.
How do you find Rth (or Zth) when a network contains dependent sources?
Deactivate only independent sources, apply a test source (1 V or 1 A) at the terminals, find the resulting terminal current or voltage, and compute Rth = Vtest/Itest. Alternatively Rth = Voc/Isc.
State Norton's Theorem.
Any linear two-terminal network can be replaced by an equivalent circuit consisting of a single current source IN (the short-circuit current at the terminals) in parallel with a single resistance/impedance RN equal to the Thevenin resistance.
How is the Norton current IN determined?
IN is the current that flows through a short circuit placed across the two output terminals (the short-circuit current).
What is the relationship between Thevenin and Norton equivalents?
They are source transformations of each other: RN = Rth, IN = Vth/Rth, and Vth = IN·RN. Both produce identical terminal behavior.
State the relation linking Voc, Isc, and Rth/RN.
Rth = RN = Voc/Isc, where Voc = Vth is the open-circuit voltage and Isc = IN is the short-circuit current.
State the Maximum Power Transfer Theorem for a purely resistive DC circuit.
Maximum power is delivered to the load when the load resistance equals the Thevenin (source) resistance, i.e. RL = Rth.
What is the maximum power delivered to the load in a resistive circuit, and the efficiency at that point?
Pmax = Vth²/(4·Rth), delivered when RL = Rth. The efficiency at maximum power transfer is only 50%.
State the Maximum Power Transfer condition for an AC circuit with complex source impedance Zth = Rth + jXth.
Maximum power transfer occurs when the load impedance is the complex conjugate of the Thevenin impedance: ZL = Zth* = Rth − jXth.
For an AC circuit, if only the load resistance is adjustable (load reactance fixed at zero), what value of RL gives maximum power?
RL = |Zth| = √(Rth² + Xth²), the magnitude of the Thevenin impedance.
What is the time constant of an RC circuit and its physical meaning?
τ = RC (seconds). It is the time for the capacitor voltage to rise to ~63.2% of its final value during charging, or fall to ~36.8% during discharging.
Write the capacitor charging voltage equation for an RC circuit with supply V.
vc(t) = V(1 − e^(−t/RC)), where the current is i(t) = (V/R)e^(−t/RC).
What is the time constant of an RL circuit and the current growth equation?
τ = L/R (seconds). Current growth: i(t) = (V/R)(1 − e^(−t·R/L)), reaching ~63.2% of final value in one time constant.
In steady state DC, how do an inductor and a capacitor behave?
At DC steady state an inductor acts as a short circuit (zero voltage across it) and a capacitor acts as an open circuit (zero current through it).
Define the resonant frequency of a series RLC circuit.
At resonance XL = XC, giving f₀ = 1/(2π√(LC)). At resonance the series RLC impedance is minimum and purely resistive (= R), so current is maximum.
Define the quality factor Q of a series RLC circuit at resonance.
Q = ω₀L/R = 1/(ω₀CR) = (1/R)√(L/C). It measures selectivity; Q = f₀/BW (resonant frequency divided by bandwidth).
What is the bandwidth of a series RLC resonant circuit?
BW = R/L = f₀/Q (in rad/s, BW = R/L; in Hz, BW = R/(2πL)). It is the difference between the two half-power (−3 dB) frequencies.
Compare the impedance behavior of series vs parallel RLC circuits at resonance.
A series RLC circuit has minimum impedance (= R) and maximum current at resonance; a parallel RLC (tank) circuit has maximum impedance and minimum line current (acts as a rejector/anti-resonant circuit).
Classify the damping of a second-order RLC circuit by damping ratio ζ.
ζ > 1: overdamped (two real roots, no oscillation); ζ = 1: critically damped (fastest non-oscillatory response); ζ < 1: underdamped (oscillatory decay); ζ = 0: undamped (sustained oscillation).
Planning Network Theory for UPSC ESE E&T
Network Theory is about 18% of the UPSC ESE E&T syllabus by topic count — 11 of 60 topics, spread over 3 chapters. At roughly 45 minutes per topic plus 12 minutes per sub-topic, a first pass runs to about 8 hours.
The heaviest chapters are Network Theorems (4 topics), Two-Port Networks (4 topics), Transient and Steady-State Analysis (3 topics) . Front-load those while your energy is high; the short chapters are better revision filler later.
Work top-down: read the chapter, then tick topics off individually rather than marking the whole chapter done. Sub-topics are where silent gaps hide.
Network Theory (UPSC ESE E&T) FAQ
What is in the UPSC ESE E&T Network Theory syllabus?
Network Theory is split into 3 chapters — Network Theorems, Transient and Steady-State Analysis and Two-Port Networks, containing 11 topics and 0 sub-topics in total.
How many chapters are there in Network Theory for UPSC ESE E&T?
3 chapters. Network Theory accounts for about 18% of the topics in the whole UPSC ESE E&T syllabus (11 of 60).
How long should I spend on Network Theory for UPSC ESE E&T?
Budget around 8 hours for a first pass through Network Theory — about 45 minutes per topic plus 12 minutes per sub-topic across its 11 topics. Add revision cycles on top.
Are there flashcards for UPSC ESE E&T Network Theory?
Yes — a 51-card Network Theory deck. Sample cards are printed on this page, and the full deck is free in the Examius app with spaced repetition scheduling.