# Multiple Questions and Answers On Network Theory

1)   In any linear network, the elements like inductor, resistor and capacitor always_________

a. Exhibit changes due to change in temperature
b. Exhibit changes due to change in voltage
c. Exhibit changes due to change in time
d. Remains constant irrespective of change in temperature, voltage and time

ANSWER: (d) Remains constant irrespective of change in temperature, voltage and time

2)   Which type of networks allow the physical separability of the network elements (resistors, inductors & capacitors) for analysis purpose?

a. Lumped Networks
b. Distributed Networks
c. Unilateral Networks
d. Bilateral Networks

3)   Which law plays a significant role in the loop analysis of the network?

a. KCL
b. KVL
c. Law of Superposition Theorem
d. None of the above

4)   How is the loop analysis different in application/functioning level as compared to Kirchoff’s law?

a. Utilization of loop currents instead of branch currents for writing equations
b. Capability of branch current to carry multiple networks
c. Reduction in the number of unknowns for complex networks
d. All of the above

ANSWER: (d) All of the above

5)   Which theorem assists in replacement of an impedance branch over the network by the other network comprising different circuit components, without affecting the V-I relations throughout the entire network?

a. Superposition Theorem
b. Compensation Theorem
c. Substitution Theorem
d. Maximum Power Transfer Theorem

6)   What should be done, if the dependent current and voltage sources are present in a circuit while applying ‘Superposition Theorem’?

a. Replace them by open circuit
b. Replaced them by short circuit
c. Keep in their original form without replacing by either open or short circuits
d. None of the above

ANSWER: Keep in their original form without replacing by either open or short circuits

7)   Which is the correct sequential order of steps to be undertaken while applying Thevenin’s theorem?

A. Calculation of Thevenin’s equivalent voltage
B. Removal of branch impedance through which required current is to be estimated
C. Estimation of equivalent impedance between two terminals of the branch
D. Estimation of branch current by schematic representation of Thevenin’s equivalent circuit

a. A, C, B, D
b. B, A, C, D
c. D, A, C, B
d. B, C, D, A

9)   Which among the below specified assertions are precisely related to the conditions applicable for a path to be an improper subgraph?

A. Incidence of a single branch at a terminating node
B. Incidence of two branches at the remaining nodes

a. A is true & B is false
b. A is false & B is true
c. Both A & B are true
d. Both A & B are false

ANSWER: (c) Both A & B are true

10)   How many number of minimum end nodes or terminal nodes are involved in a tree, according to its properties?

a. Only one
b. Two
c. Four
d. Infinite

11)   What will be the value of a rectangular (complete incidence) matrix, if an associated branch is oriented towards the node?

a. 1
b. -1
c. 0
d. Not defined (∞)

12)   According to the linear graph theory, the number of possible trees is always equal to the determinant of product of ______

a. Only complete incidence matrix
b. Reduced incidence matrix & its transpose
c. Cut-Set matrix
d. Tie-set matrix

ANSWER: (b) Reduced incidence matrix & its transpose

13)   Consider the mathematical representation of nth order differential equation given below. What does the notation v(t) indicate in it?

a0 (dn i/dtn) + a1 (dn -1 i /dtn-1) + …… +a n-1 (di / dt) + an i = v(t)
a. Independent variable
b. Input or forcing function
c. Excitation
d. All of the above

ANSWER: (d) All of the above

14)   If a differential equation is said to be homogeneous, what would be the value of a forcing function?

a. 0
b. 1
c. ∞
d. -1

15)   Which notation of instant implies that the unchanged condition of network is about to change?

a. t(0)+
b. t(0)
c. t*
d. tˆ

16)   Which elements behave as an open circuit especially under the consideration of d.c. quantities?

a. Inductors
b. Resistors
c. Capacitors
d. All of the above

17)   What would be the value of power factor for series RLC circuit under the resonance phenomenon?

a. 0
b. 0.5
c. 1
d. Infinity

18)   Which among the following get/s cancelled under the resonance condition in a.c. circuits, if inductive and capacitive reactances are in parallel?

a. Reactance
b. Susceptance
c. Resistance
d. All of the above

19)   Which among the following condition is true at the resonance?

a. Xc > XL
b. Xc = XL
c. Xc < XL
d. None of the above

20)   Reactance curve is basically a graph of individual reactances verses __________

a. Frequency
b. Phase
c. Amplitude
d. Time period

21)   Which type of impedance in asymmetrical network is estimated at a single pair of network terminals especially in the chain of infinite networks?

a. Image impedance
b. Iterative impedance
c. Characteristic impedance
d. All of the above

22)   Where do the ‘correctly terminated asymmetrical networks’ show termination at both the ports of network?

a. In image impedances
b. In iterative impedances
c. In characteristic impedances
d. All of the above

23)   Which unit is used for the measurement of an insertion loss?

a. Neper
b. Weber
c. Ohm
d. Watt

24)   How is an insertion loss represented in terms of power ratio?

a. α = 10 log10 | P1 / P2 | decibel
b. α = 10 log10 | P2 / P1 | decibel
c. α = 20 log10 | P1 / P2 | decibel
d. α = 20 log10 | P2 / P1 | decibel

ANSWER: (a) α = 10 log10 | P1 / P2 | decibel

25)   Which type of filter is shown below? a. Low pass filter
b. High pass filter
c. Band pass filter
d. Band elimination filter

26)   While designing a constant-k low pass filter (T-section) shown below, what would be the value of capacitor if L/2 = 20mH, R0 = 500 Ω and fc = 5 kHz? a. 0.0635 μF
b. 0.10 μF
c. 0.1273 μF
d. 0.20 μF

27)   For a constant k type LPF with T- section, with the cut-off frequency of about 4kHz, what will be the value of stop-band attenuation at 8 kHz? a. 10.03 dB
b. 22.87 dB
c. 35.04 dB
d. 50.02 dB

28)   Referring to the characteristics of π-section low pass filter given below, what would be the phase shift at 2kHz in the pass band? 29)   Which type of attenuators provide a fixed amount of attenuation by allowing the user to vary the attenuation in multiple steps?

b. Variable-value attenuators
d. All of the above

30)   For the symmetrical ‘T’ attenuator shown below, what would be the value of shunt arm resistance with N = 10 & design impedance = 500 ohm? a. 51.21 ohm
b. 101.01 ohm
c. 305.90 ohm
d. 409.90 ohm

31)   Consider the assertions given below. Which of them is not a disadvantage of Laplace Transform?

a. Unsuitability for data processing in random vibrations
b. Analysis of discontinuous inputs
c. Possibility of conversion s = jω is only for sinusoidal steady state analysis
d. Inability to exist for few Probability Distribution Functions

ANSWER: (b) Analysis of discontinuous inputs

32)   What does ‘σ’ indicate in the equation of complex frequency variable s = σ + jω while defining the laplace transform?

A. Attenuation constant
B. Damping factor
C. Propagation constant
D. Phase constant

a. A & B
b. C & D
c. B & C
d. B & D

33)   How does the ‘σ’ of complex frequency variable appear in time domain?
a. As a linear power
b. As a reactive power
c. As an exponential power
d. As an iterative power

ANSWER: (c) As an exponential power

34)   In the pictorial schematic shown below, what would be the equation of time domain behaviour produced due to complex frequency variable for σ > 0? a. eσt sin ωt
b. eσt cos ωt
c. eσt sin ωt + eσt cos ωt
d. eσt sin ωt – eσt cos ωt

35)   In the circuit, the driving point impedance is (s + 5) / (s2 + 5s + 1). Hence, the driving point admittance of the circuit is __________ a. (s + 5)
b. (s2 + 5s + 1)
c. (s + 5) x (s2 + 5s + 1)
d. (s2 + 5s + 1) / (s + 5)

ANSWER: (d) (s2 + 5s + 1) / (s + 5)

36)   Compute the voltage ratio transfer function for the network shown below. Assume that the current flowing through the branch between node ‘a’ & ‘Q’ is (Ia + 4 Ia) i.e. 5Ia a. -3/7
b. -5/11
c. -3/11
d. -5/7

37)   Transfer admittance function is the ratio of Laplace transforms of ________

a. Current at one port to voltage at other port
b. Voltage at one port to current at other port
c. Current at one port to current at other port
d. Voltage at one point to voltage at other port

ANSWER: (a) Current at one port to voltage at other port

38)   When a network function is expressed as a ratio of Laplace transforms of output to input variables of a system, then it is regarded as _______

a. System function
b. Transfer function
c. Both a and b
d. None of the above

ANSWER: (c) Both a and b

39)   What does the connectivity of energy source at the port of network known as?

a. Driving Point
b. Transfer Point
c. Both a and b
d. None of the above

40)   For the network given below, what would be the value of ‘z22‘, if the estimated z-parameters are ‘z11‘ = 30 and ‘z12‘ = ‘z21‘ = 10? a. 10
b. 20
c. 30
d. 40

41)   What is the potential value of a reference or datum node used in the node analysis of a network?

a. Zero
b. Unity
c. Greater than zero but less than infinity
d. Unpredictable

42)   What will be the value of equivalent single source, if the two voltage sources connected in series combination possess equal or similar polarity?

a. Addition of two sources with polarities similar to that of two sources
b. Addition of two sources with opposite polarity
c. Difference between the two sources with polarities similar to that of two sources
d. Difference between the two sources with polarities similar to that of greater among the two sources

ANSWER: (a) Addition of two sources with polarities similar to that of two sources

43)   What should be the value of resistance for the circuit diagram shown below? a. Zero
b. Infinity
c. Unity
d. Cannot be predicted

44)   What should be the value of I2 in accordance to mesh current method for the below drawn circuit diagram? a. 1.39 A
b. 1.63 A
c. 2.33 A
d. 5 A

45)   Which among the following is also regarded as ‘Dual of Thevenin’s Theorem’?

a. Norton’s Theorem
b. Superposition Theorem
c. Millman’s Theorem
d. Maximum Power Transfer Theorem

46)   What would be the nature of ‘ZL‘, if ‘Zeq‘ reactance is inductive according to ‘Maximum power transfer theorem’?

a. Inductive
b. Capacitive
c. Resistive
d. All of the above

47)   Which value of load impedance (ZL) is necessary to be connected across the terminals R-S for maximum power transfer in the network shown below ? a. 5 + j5 Ω
b. 5 – j5 Ω
c. 10 + j10 Ω
d. 10 – j10 Ω

ANSWER: (d) 10 – j10 Ω

48)   What is the value of impedance ‘Z2‘ according to Miller’s theorem for the network shown below? a. Z.K /K-1
b. Z /1-K
c. Z /K-1
d. Z-1 /K

49)   What will be the number of trees, if the graph exhibits reduction in the form of reduced incident matrix given below? a. 16
b. 24
c. 26
d. 28

50)   How many fundamental cutsets will be generated for a graph with ‘n’ number of nodes?

a. n+1
b. n-1
c. n2(n-1)
d. n/ n-1

51)   Which parameter should be essentially equal to the number of nodes in the network in accordance to the principle of duality?

a. Total impedance
c. Number of meshes
d. Number of voltage sources

52)   Consider the assertions given below. Which among them do/does not specify/ies the property of ‘Complete Incidence Matrix’?

a. Determinant of a loop of a complete incidence matrix is always zero
b. Addition of all entries in any column should never be equal to zero
c. Rank of connected or oriented graph is always ‘n-1’
d. All of the above

ANSWER: (b) Addition of all entries in any column should never be equal to zero

53)   Which type of network response exhibits its behaviour by taking into consideration the effect of time associated with it?

a. Zero input response
b. Zero state response
c. Both a and b
d. None of the above

54)   From the diagram given below showing characteristics of voltage across resistor and inductor with respect to time, what conclusion can be drawn due to exponential growth of current through inductor? a. Voltage across resistor and inductor increases
b. Voltage across resistor and inductor decreases
c. Voltage across resistor increases but decreases across inductor
d. Voltage across resistor decreases but increases across inductor

ANSWER: (c)Voltage across resistor increases but decreases across inductor

55)   Consider the circuit drawn below. What would be the value of i(0) especially when the inductor acts as a short circuit? a. 0.3 A
b. 2 A
c. 5 A
d. 10 A

56)   How many seconds will be required for the current i(t) to become one half of its initial value after t = 0 in the below drawn network a. 866 μs
b. 1039 μs
c. 1200 μs
d. 1849 μs

57)   How do the series resonant circuit behave under the resonance condition?

a. Current amplifier
b. Transconductance
c. Voltage regulator
d. Voltage amplifier

58)   If an a.c. signal generator drives a series RLC circuit, then the circuit undergoes resonance only due to variation in __________

a. Supply voltage
b. Series resistance
c. Supply frequency
d. Phase angle

59)   The current leads supply voltage if a series resonant circuit exhibits its operation__________ the resonant frequency

a. Above
b. Below
c. Equal to
d. None of the above

60)   What would be the value of impedance of a parallel resonant circuit at antiresonance condition?

a. Resistive & maximum
b. Resistive & minimum
c. Reactive & maximum
d. Reactive & minimum

61)   What would be the characteristic impedance of a T-section for symmetrical network shown below? a. 300.15 ohm
b. 529.15 ohm
c. 715.15 ohm
d. 900.15 ohm

62)   Consider the symmetrical T-network shown below. What will be the value of propagation constant, if characteristic impedance is estimated to be Z0 = 850.64 ohm? a. 0.2824 neper
b. 0.1412 neper
c. 0.0706 neper
d. 0.0353 neper

63)   Consider the below mentioned assumptions of two symmetrical T networks in cascade configuration. What will be the value of current flowing through terminating impedance for the network configuration shown below?

Assumptions:
n = -2,
? = 1.5,
Is = 0.6 A a. 0.0112 A
b. 0.0298 A
c. 0.04145 A
d. 0.0812 A

64)   If a network comprises purely resistive elements, what will it provide from the following?

a. Attenuation
b. Phase Shift
c. Both a and b
d. None of the above

65)   What do the high pass filters generally comprise of?

A. Capacitive series arm
B. Capacitive shunt arm
C. Inductive series arm
D. Inductive shunt arm

a. A & D
b. A & C
c. B & C
d. B & D

66)   For the design of prototype high pass filter T section, what would be the value of inductor if design impedance and cut-off frequency are 600 ohm and 1500 Hz respectively? a. 19.89 mH
b. 31.83 mH
c. 40.13 mH
d. 51.83 mH

67)   In band elimination filter, the frequency of resonance of individual arms is geometric _________

a. Mean of two cut-off frequencies
b. Difference of two cut-off frequencies
c. Product of two cut-off frequencies
d. Division of two cut-off frequencies

ANSWER: (a) Mean of two cut-off frequencies

68)   Which value of ‘m’ is selected in a composite filter, while connecting the terminating sections in order to acquire proper impedance matching and constant characteristic impedance throughout the passband?

a. 0.3
b. 0.6
c. 0.9
d. 0.12

69)   Referring to the schematic of symmetrical π attenuator below, what will be the computational value of attenuation in neper, if D = 20 dB & R0 = 400 ohm? a. 10
b. 20
c. 40
d. 80

a. For speed control
b. For volume control
c. For time control
d. For power control

71)   With reference to the diagram shown below, by how many instants is the ramp function shifted or delayed? a. T
b. t – T
c. 1
d. -T

72)   Consider a function f(t) that satisfies the differential equation given below. What equation will be generated by taking Laplace transform and replacing the terms f(0) & f'(0) by zero?

[d2 f(t) / dt2] + 5 [df(t) / dt ] + 6 f (t) = 10

a. [S2 F(s) + 5s F(s)+6 F(s)] = 10/s
b. [S2 F(s) + 5s F(s) – 6 F(s)] = 10/s
c. [S2 F(s) – 5s F(s) + 6 F(s)] = 10/s
d. [S2 F(s) – 5s F(s) – 6 F(s)] = 10/s

ANSWER: (a) [S2 F(s) + 5s F(s)+6 F(s)] = 10/s

73)   In accordance to Laplace domain theory, the transform admittance of resistance is _______

a. Impedance
b. Conductance
c. Inductance
d. Capacitance

74)   From the circuit diagram shown below, what would be the value of transform impedance of a single capacitor in Laplace domain? a. 1 / sC
b. sC
c. sC – 1
d. sC / 1+ sC

75)   What does the value of constant ‘k’ represent in the factorized form of network equation given below?
H(s) = [k (s – z1) (s – z2) —– (s – zm)] / [(s – p1) (s – p2) ….. (s – pn)]

A. System gain factor
B. Scale factor
C. Vector factor
D. System quality factor

a. A & B
b. C & D
c. A & C
d. B & D

76)   If the complex system function is analytic in nature, the points in s-plane are regarded as ________

a. Ordinary points
b. Singular points
c. Multiple points
d. All of the above

77)   Which among the following belong/s to the category of critical frequency?

a. Poles
b. Zeros
c. Both a and b
d. None of the above

ANSWER: (c) Both a and b

78)   What is an ideal value of network function at poles?

a. Zero
b. Unity
c. Infinity
d. Finite and non-zero

79)   Which elements act as an independent variables in Y-parameters?

a. Current
b. Voltage
c. Both a and b
d. None of the above

80)   Which among the following is regarded as short circuit forward transfer admittance?

a. y11
b. y12
c. y21
d. y22

81)   Under which conditions does the source transformation technique remain directly unapplicable?
a. Only in the absence of impedance in series with a voltage source
b. Only in the absence of impedance in parallel with a current source
c. Both a and b
d. None of the above

ANSWER: (c) Both a and b

82)   If innumerable branches are present in parallel configuration in a network, which method approves to be extensively beneficial for network analysis?

a. Node method
b. Mesh method
c. Both a and b
d. None of the above

83)   Which operation is likely to get executed or performed by Millman’s theorem in terms of converting the voltage or current sources into a single equivalent voltage or current source?

a. Subtraction
b. Combination
c. Differentiation
d. Integration

84)   Why does the Superposition theorem not applicable to power?

a. Because it is proportional to square of current and current is a non-linear function
b. Because it is proportional to square of voltage and voltage is a non-linear function
c. Both a and b
d. None of the above

ANSWER: (a) Because it is proportional to square of current and current is a non-linear function

85)   What would be an order of branch impedance matrix for the below stated KVL equilibrium equation on the basis of loop or mesh analysis?

E = B (Vs – Zb Is)

a. b x 1
b. b x b
c. b-n+1) x 1
d. (b-n+1) x b

86)   According to the graph theory of loop analysis, how many equilibrium equations are required at a minimum level in terms of number of branches (b) and number of nodes (n) in the graph?

a. n-1
b. b+(n-1)
c. b-(n-1)
d. b/ n-1

87)   What would be the nature of roots for undamped type of circuits with sustained oscillations?

a. Purely imaginary
b. Real, equal & negative
c. Complex conjugate with negative real part
d. Real, unequal & negative

88)   What will be the value of the time required by the response to reach 50% of its steady state value for second order system?

a. π – θ /ωd
b. π / ωd
c. 4 / ξ ωn
d. (1+ 0.7 ξ) /ωn

ANSWER: (d) (1+ 0.7 ξ) /ωn

89)   What will be the nature of impedance at a frequency below the antiresonant frequency?

a. Capacitive
b. Inductive
c. Reactive
d. Resistive

90)   If the value of resonant frequency is 50 kHz in a series RLC circuit along with the bandwidth of about 1 kHz, then what would be the value of quality factor?

a. 5
b. 50
c. 100
d. 500

91)   What would be the value of attenuation constant especially for the network consisting of purely reactive elements?

a. 0
b. 1
c. -1
d. Infinity

92)   Suppose that a network consists of purely resistive elements, what will be the value of propagation constant (generated output) in terms of attenuation constant and phase constant from the following?

a. γ = α + j0
b. γ = 0 + jβ
c. γ = 0 – jβ
d. γ = α – j0

ANSWER: γ = α + j0

93)   It is possible to overcome the drawback of m-derived filter by connecting number of sections in addition to prototype & m-derived sections with terminating __________

a. One-fourth sections
b. Half sections
c. Square of three-fourth sections
d. Full sections

94)   What is an ideal value of attenuation for the frequencies in pass band especially for a cascade configuration?

a. Zero
b. Unity
c. Infinity
d. Unpredictable

95)   Variable attenuators exhibit variable attenuation but constant __________

a. Input impedance
b. Output impedance
c. Both a and b
d. None of the above

ANSWER: (c) Both a and b

96)   In accordance to the circuit configuration of bridged ‘T’ variable attenuator below, how many resistors should be varied in order to achieve variable attenuation? a. Only one
b. Two
c. Three
d. Four

97)   If the value of (P1 / P2) in power ratio expressed in terms of dB is greater than unity, what does ‘D’ indicate in the network?

a. Power loss
b. Power gain
c. Power stability
d. Power saving

98)   What will be the driving point impedance of Laplace domain network shown below? a. (10s2 + 5.25s + 1.5) / (s+0.125)
b. (6s2 + 2.25s + 1.5) / (s+0.25)
c. (5s2 + 2.25s + 1.5) / (s+0.16)
d. (8s2 + 2.25s + 1.5) / (s+0.8)

ANSWER: (a) (10s2 + 5.25s + 1.5) / (s+0.125)

99)   Consider the RC circuit shown below. What will be the value of time constant for RC circuit? a. 0.25 sec
b. 0.50 sec
c. 1 sec
d. 2 sec

100)   What would be the value of i(t) especially for t > 0 in the RC circuit shown below? [Assume that the polarities of vc (0) are similar to the drop across capacitor due to i(t)] a. -2.125 e-1t A
b. -4.125 e-2t A
c. -8 e-4t A
d. -10 e-5t A

101)   For the pole-zero plot given below, what would be the value of system function H(s), if the d.c. gain of the system is 20? a. 10 (s + 4) / (s + 1) (s2 + 6s – 10)
b. 20 (s – 4) / (s + 3) (s2 _ 6s +10)
c. 40 (s + 4) / (s + 3) (s2 – 6s – 10)
d. 50 (s + 4) / (s + 1) (s2 + 6s +10)

ANSWER: (d) 50 (s + 4) / (s + 1) (s2 + 6s +10)

102)   Which oscillations will be generated in the time domain response, if complex conjugate poles are present with negative real part?

a. Damped oscillations
b. Undamped oscillations
c. Sustained oscillations
d. None of the above

103)   Which among the below mentioned cases are responsible for generating the oscillations with increasing amplitude in time domain response of system function?

A. Complex poles with positive real part
B. Complex poles with negative real part
C. Repeated poles on imaginary axis
D. Repeated poles on real axis

a. A & C
b. B & D
c. B & C
d. A & D

104)   How is the short circuit reverse transfer admittance (y12) calculated in terms of current and voltage ratio?

a. V2/ I1 (keeping I2 = 0)
b. I2/ V1 (keeping V2 = 0)
c. I1/ V2 (keeping V1 = 0)
d. V1/ I2 (keeping I1 = 0)

ANSWER: (c)  I1/ V2 (keeping V1 = 0)

105)   An open circuit reverse voltage gain in h-parameters is a unitless quantity and generally equivalent to ________

a. V1 / I1 (keeping V2 = 0)
b. I2 / I1 (keeping V2 = 0)
c. V1 / V2 (keeping I1 = 0)
d. I2 / V2 (keeping I1 = 0)

ANSWER: (c) V1 / V2 (keeping I1 = 0)

106)   Which is the correct condition of symmetry observed in z-parameters?

a. z11 = z22
b. z11 = z12
c. z12 = z22
d. z12 = z21

107)   Which among the following represents the precise condition of reciprocity for transmission parameters?

a. AB – CD = 1
b. AD – BC = 1
c. AC – BD = 1
d. None of the above

108)   If the two ports are connected in cascade configuration, then which arithmetic operation should be performed between the individual transmission parameters in order to determine overall transmission parameters?

b. Subtraction
c. Multiplication
d. Division

109)   If z-parameters are z11 = 40, z22 = 50 and z12 = z21 = 20, what would be the value of y22in the matrix form of y-parameters given below? a. 4 / 160
b. 5 / 160
c. 10 / 160
d. 15 / 150