ENGINEERING FUNDA YOUTUBE CHANNEL BY PROF. HITESH DHOLAKIYA
NETWORK THEORY & ANALYSIS
Q-1 What is resistance?
Ans The resistance is the property of a material to oppose the flow of current in a
material.its unit is ohm.
Q-2 What are the material used for resistor?
Ans The material used are maganin (alloy of copper magnese and nickel), constantan
(alloy of nickel and copper).
Q-3 What is inductance?
Ans It is the property of a material by virtue of which it opposes any change of
magnitude and direction of current passing through the conductor.
Q-4 What happens to voltage when current through the inductor is constant?
Ans The voltage across inductor is zero.
Q-5 How will you define capacitance?
Ans It is the ability to store electric charge within it. Capacitance is a measure of
charge per unit voltage that can be stored in an element.
Q-6 What happens to voltage when current is zero?
Ans The voltage is constant.
Q-7 When we use 3 terminal resistor?
Ans It is used when resistance is less than 1 ohm.
Q-8 What is the unit of charge and current?
Ans The units are coulomb and ampere.
Q-9 What are the properties of a resistor?
Ans The properties are high resistivity resistance to oxidation, corrosion and
moisture.
Q-10 What is Q factor?
Ans The Q factor is ratio of inductive reactance to resistance of a coil.
Q-11 What are the material used for inductance coil?
Ans The materials used are marble because it is unaffected by atmospheric
conditions.
Q-12 Which capacitor is preferred for high voltage and frequency?
Ans The vacuum and gas filled capacitor are used for high voltage and frequency
applications.
Q-13 State Kirchoff current law?
Ans The algebraic sum of currents at any node of a circuit is zero. The sum of
incoming current is equal to sum of outgoing current.
Q-14 What are dependent sources?
Ans When strength of voltage or current changes in the source for any change in the
connected network they are called dependent sources.
Q-15 List examples of voltage source?
Ans The examples of voltage source are battery and generator.
Q-16 List examples of current sources?
Ans Semiconductor devices like transistor and diode are treated as current sources.
Q-17 State Kirchhoff voltage law?
Ans Kirchoff voltage law states that the algebraic sum of all branch voltages around
any closed loop of a network is zero at all instant of time.
Q-18 State Thevenin Theorem?
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Ans This theorem states that any linear network with output terminal AB can be
replaced by a single voltage source V in series with a single impedance.
Q-19 How equivalent impedance is calculated in Thevenin Theorem?
Ans All independent voltage sources are short circuited and all independent current
sources are open circuited.
Q-20 What is the limitation of Kirchhoff’s law?
Ans It fails in distributed parameter network.
Q-21 State Norton’s theorem?
Ans This theorem states that any linear bilateral network with active network with
output terminals AB Can be replaced by a single current source in parallel with a
single impedance Z.
Q-22 Is the theorem applicable to ac sources?
Ans No it is applicable to dc circuits with and without controlled sources.
Q-23 Define Norton equivalent circuit?
Ans The Norton equivalent circuit is a current generator which is placed in parallel to
internal resistance.
Q-24 State Superposition theorem?
Ans If a number of voltages or current sources are acting simultaneously in a linear
network the resultant current in any branch is the algebraic sum of current that
would be produced in it when each source acts alone replacing all other
independent sources by their internal resistances.
Q-25 Sate Maximum power transfer theorem?
Ans A resistance load being connected to a dc network receives maximum power
when load resistance is equal to internal resistance.
Q-26 What is the efficiency during maximum power transfer?
Ans 50percent
Q-27 Define branch?
Ans It is a part of a network which lies between two junction points.
Q-28 Define active and passive network?
Ans The network which has no current or voltage source is called passive network.
The network which either has current or voltage source is called active network.
Q-29 State Ohm’s Law?
Ans The current through any conductor is directly proportional to the applied
potential difference across it keeping physical condition unchanged.
Q-30 Define unilateral circuit?
Ans The circuit whose properties are not same in either direction is known as
unilateral circuit.
Q-31 Define integrating circuit?
Ans Integrator is a electronic circuit where output signai is the integral of the input
waveform.
Q-32 Is the integrator a low pass filter?
Ans Low pass filter.
Q-33 What is differentiating circuit?
Ans The electronic circuit where output voltage is the differentiation of input
waveform.
Q-34 Is the differentiator a high pass filter?
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Ans Yes.
Q-35 What is the role of feedback resistor in integrator?
Ans Both the stability and the low frequency roll off problem can be corrected by
addition of feedback resistor.
Q-36 What is output when input to integrator is sine wave?
Ans The output is cosine wave.
Q-37 What happens to gain with increase in gain of integrator?
Ans The gain decreases with 20 dB/ decade.
Q-38 What is the purpose of r and feedback capacitor in differentiator?
Ans Both stability and high frequency noise problems can be crrected with R and C.
Q-39 What happens to gain when frequency increases in differentiator?
Ans The gain increases with 20 dB/decade.
Q-40 What are applications of differentiator?
Ans It is most commonly used in wave shaping circuit to detect high frequency
component and also as a rate of change detector in FM modulators.
Q-41 Define filter?
Ans A network designed to attenuate certain frequencies but pass others without
attenuation is called filter. A filter circuit thus possess at least one pass band
which is a band of frequency in which output is approximately equal to input and
an attenuation band in which output is zero.
Q-42 What are factors on which accuracy depends?
Ans The factors are signal to noise ratio, response time and bw over which
measurement are desired.
Q-43 What are elements of passive filter?
Ans The elements are inductor, capacitor and resistor.
Q-44 Define design impedance?
Ans It is a T filter in which series arm Z1 and shunt Z2 are connected by relationship
Z1*Z2 =R*Rcalled impedance design.
Q-45 Define low pass filter?
Ans The gain is constant over a frequency range starting from zero to cut-off
frequency .The output of any signal having a frequency greater than cutt off
frequency will be attenuated there will be no output voltage for frequencies
greater than f.
Q-46 Define high pass filter?
Ans The high pass filter has a zero gain starting from zero to cutt off frequency.
Above this cutt off frequency gain is constant equal to A.
Q-47 Define all pass filter?
Ans In this filter all frequencies are passed without attenuation .The important
features of this filter is that it provides predictable phase shift for frequencies of
different input signals.
Q-48 What are advantages of active filter over passive filter?
Ans The advantages are 1. Gain and frequency adjustment flexibility. 2. No loading
problem 3. Cost is low.
Q-49 What is the slope of first order low pass Butterworth filter?
Ans The slope is -20dB/deacde.
Q-50 What is the slope of first order high pass Butterworth filter?
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Ans The slope is +20dB/deacde.
Q-51 Explain Ohm’s law?
Ans “The current passing through a conductor is directly proportional to the potential
difference across the ends of the conductor “
Q-52 What are limitations of Ohms law?
Ans The main limitation of Ohm’s law is that physical dimension of the conductor
should not change with temperature.
Q-53 Define current?
Ans The rate of change of charge with respect to time is called electric current.
Q-54 Explain Kirchhoff’s current law?
Ans According to Kirchhoff’s current law” in any network of conductors in an
electrical circuit the algebraic sum of the current in all the conductors meeting at
any point is zero.
Q-55 Explain electric field strength?
Ans Electric field strength at any point is define as the mechanical force experienced
by a unit positive charge placed at that point in the electric field.
Q-56 Define resistivity?
Ans The resistance offered by one meter length of wire having an area of cross
section of one square meter is called the resistivity of material.
Q-57 Define conductance?
Ans The ease to the flow of current is called conductance.
Q-58 What do you mean by a Conductivity?
Ans Conductivity is basically the property or nature of the material due to which it
allows the current to flow through it.
Q-59 What do you mean by an electrical power?
Ans The rate at which work is being done ia an electrical circuit is called electrical
power.
Q-60 What do you mean by a heat energy?
Ans The form of energy which produces a sensation of warmth is called heat.
Q-61 Define resonance?
Ans Resonace in electrical circuit consist of passive and active elements represents a
particular state of circuit when current or voltage in the circuit is maximum or
minimum.
Q-62 What is the value of power factor?
Ans Power factor is 1.
Q-63 What is the phase difference between voltage and current in a inductor?
Which is leading?
Ans Phase difference is 90 degree and voltage is leading.
Q-64 What is the phase difference between voltage and current in a capacitor?
Which is leading?
Ans Phase difference is 90 degree and current is leading.
Q-65 Define selectivity?
Ans The selectivity of a resonating circuit is defined as ratio of frequency of
resonance to bandwidth of the circuit.
Q-66 Define bandwidth?
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Ans The frequency band within the limits of lower and upper half power frequency is
called bandwidth.
Q-67 What is the effect of resistance in RLC circuit?
Ans The effect is to flatten the curve.
Q-68 Which circuit is more responsive?
Ans The circuit with flat response is more responsive.
Q-69 For RLC circuit what is power factor at lowest power frequency?
Ans The power factor is 0.707 leading.
Q-70 What is the locus of voltage phaser across R in series RLC circuit?
Ans The phasor is circle.
Q-71 Define filter?
Ans A filter is an electrical network that can transmit signals within a specified
frequency range
Q-72 List the characteristics of filter?
Ans An ideal filter would transmit signals under the pass band frequencies without
attenuation and completely suppress the signal with attenuation band of
frequencies with a sharp cutt off profile.
Q-73 Define characteristics impedance?
Ans The characteristics impedance of a filter matches with circuit to which it is
connected throughout the pass band.
Q-74 What is the unit of attenuation?
Ans The unit is decibel and neper.
Q-75 What are the application of filter?
Ans The Filter is used in voice frequency telegraphy, multichannel communication,
TV broadcasting and telephony.
Q-76 Define active filter?
Ans The active filter contains components like operational amplifier that introduce
some gain in the signal.
Q-77 List advantages of active filter over passive filter?
Ans Active filter eliminate bulky components. It offer gain. It can drive low
impedance loads. It is easy to tune.
Q-78 List the disadvantages of constant K filters?
Ans The attenuation does not increase rapidly beyond cutt off frequency.
Characteristics impedance varies widely in the pass band from desired value.
Q-79 Define cut-off frequency?
Ans The frequency that separates the pass and attenuation band is known as cutt off
frequency.
Q-80 How a band pass filter is constructed?
Ans This filter is a combination of two parallel tuned circuit. This is a special type of
LC filter along with a particular BW frequency to be allowed through it.
Q-81 In a RLC circuit What is the value of current?
Ans The current is maximum and minimum in parallel.
Q-82 Define time constant of capacitor circuit?
Ans Time constant of a capacitance may be defined as time during which voltage
rises to 63.2% of its final steady value.
Q-83 Does the value of current depends on reactance series RLC circuit?
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Ans It depends on resistance, inductive and capacitive reactance.
Q-84 Define power factor?
Ans The power factor is defined as the ratio of true power and apparent power.
Q-85 In series RLC circuit what is the phase difference between current and
voltage?
Ans Phase difference is 0 degrees.
Q-86 Define resonance curve?
Ans The resonance curve for a series circuit is a plot of current and frequency.
Q-87 Define reactive power?
Ans The product of rams voltage and current with sine of the angle between them is
called reactive power.
Q-88 Which parameter is leading in parallel RC circuit?
Ans Current leads voltage in parallel RC circuit.
Q-89 Why parallel circuit is called rejector?
Ans Because R is low, impedance is high and current is much lowerin parallel circuit.
Q-90 What happens to Z when it attains selectivity?
Ans Z is large.
Q-91 Define Q factor for parallel circuit?
Ans It is the current magnification of circuit at resonance. It represents ratio of two
current in branch.
Q-92 Define parallel resonance?
Ans In the parallel resonance capacitive current must be equal to inductive current.
This circuit is called rejector circuit.
Q-93 What is the value of power factor in parallel resonance?
Ans Power factor is unity.
Q-94 What is value of susceptance at parallel resonance?
Ans It is zero.
Q-95 What is the phase difference between current and voltage in RC parallel
circuit?
Ans The phase angle is 90
Q-96 Which quantity is leading in RC parallel circuit?
Ans Current leads voltage RC parallel circuit.
Q-97 Define selectivity?
Ans The variation of magnitude of the voltage across the capacitor with frequency
indicates that the voltage reaches a sharp peak just below resonance frequency.
This is called selectivity.
Q-98 What is the value of Q factor for RLC circuit?
Ans The Q factor is equal to voltage gain.
Q-99 Which part of impedance produce heat?
Ans Resistive
Q-100 Which part produce magnetic energy?
Ans Inductive
Q-101 Define 3dB points?
Ans The 3 dB point is the point at which power dissipation at bandwidth is half to
that of power dissipation at resonance.
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Q-102 What is network?
Ans Interconnection of two or more simple circuit elements is called an electric
network.
Q-103 Distinguish between a branch and a node of a circuit.
Ans A part of the network which connects the various points of the network with one
another is called a branch. A point at which two or more elements are jointed
together is called node.
Q-104 Distinguish between a mesh and a Loop of a circuit.
Ans A mesh is a loop that does not contain other loops. All meshed are loops. But all
loops are not meshes. A loop is any closed path of branches.
Q-105 Define active and passive elements.
Ans The sources of energy are called active element. Example: voltage source,
current source. The element which stores or dissipates energy is called passive
element. Example: Resistor, Inductor, Capacitor.
Q-106 Define unilateral and bilateral elements.
Ans In unilateral element, voltage – current relation is not same for both the
direction. Example: Diode, Transistors. In bilateral element, voltage – current
relation is same for both the direction. Example: Resistor
Q-107 Define linear and non-linear elements.
Ans If the element obeys superposition principle, then it is said to be linear elements.
Example: Resistor. If the given network is not obeying superposition principle
then it is said to be nonlinear elements. Example: Transistor, Diode.
Q-108 Define Lumped and distributed elements.
Ans Physically separable elements are called Lumped element. Example: Resistor,
Capacitor, Inductor. A distributed element is one which is not separable for
electrical purpose. Example: Transmission line has distributor resistance,
capacitance and inductance.
Q-109 How are the electrical energy sources classified?
Ans The electrical energy sources are classified into: 1. Ideal voltage source 2. Ideal
current source.
Q-110 Define an ideal voltage source.
Ans The voltage generated by the source does not vary with any circuit quantity. It is
only a function of time. Such a source is called an ideal voltage source.
Q-111 Define an ideal current source.
Ans The current generated by the source does not vary with any circuit quantity. It is
only a function of time. Such a source is called as an ideal current source.
Q-112 What are independent source?
Ans Independent sources are those in which, voltage and current are independent and
are not affected by other part of the circuit.
Q-113 What are dependent sources?
Ans Dependent sources are those in which source voltage or current is not fixed, but
is dependent on the voltage or current existing at some other location in the
circuit.
Q-114 What are the different types of dependent or controlled sources?
Ans 1. Voltage Controlled Voltage Sources (VCVS)
2.Current Controlled Voltage Sources (CCVS)
3.Voltage Controlled Current Sources (VCCS)
4.Current Controlled Current Sources (CCCS)
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Q-115 What is average value?
Ans It is defined as area under one complete cycle to period. The average value of the
sine wave is the total area under the half-cycle curve divided by the distance of
the curve.
Q-116 Define R.M.S. value.
Ans The rms value may be determined by taking the mean of the squares of the
instantaneous value of current over one complete cycle.
Q-117 Define form factor.
Ans The ratio of RMS value to the average value is called the Form factor.
Q-118 Define peak factor.
Ans Peak factor is defined as the ratio of the maximum value to the rms value.
Q-119 Write few advantages of sinusoidal waveform?
Ans 1. The response of the sinusoidal input for second order system is sinusoidal.
2. The wave form can be written in terms of sinusoidal function according to
fourier theorem.
3. The derivatives and integral also sinusoidal.
4. Easy for analyses.
5. Easy to generate.
6. More useful in power industry.
Sufficient knock or pull these electrons from their position in the crystal and
convert them in to conduction electrons. Thus zener break down voltage
decreases with temperature.
Q-120 Distinguish between a cycle, time periods and frequency.
Ans One complete set of positive and negative instantaneous values of the voltage or
current is called cycle. The time taken by an alternating quantity to complete one
cycle is called time period (T). Time period (T) = 2π/W
The number of cycle that a alternating quantity completed per second is known
as frequency. t is measured in HZ. Frequency (f) = 1/T
Q-121 What is instantaneous value?
Ans The value of an alternating current, at any particular moment is called its
instantaneous value.
Q-122 What are peak value and peak to peak value?
Ans The peak value of the sine wave during positive or negative half only. The sum
of positive and negative value is called a peak to peak value. The peak to peak
value of a sinusoidal alternating voltage is equal to two times the peak value.
Q-123 Define phasor.
Ans Graphical representation of phase-angle is known as phasor
Q-124 Define phase angle.
Ans The phase angle is the difference in phase between the voltage and the current in
an AC circuit, it’s associated with the impedance Z of the circuit.
Q-125 What is average power?
Ans The average of the instantaneous power over one period is called average power.
Average power is also defined as the product of voltage and current.
Q-126 What is power triangle?
Ans A commonly employed graphical representation of complex power is known as
the power triangle.
Q-127 Define complex power
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Ans The product of the rms voltage phasor and the complex conjugate of the rms
current phasor is known as complex power. It is denoted as S and it is measured
in volt-amperes (VA)
Q-128 What is mesh analysis?
Ans Mesh analysis is one of the basic techniques used for finding current flowing
through the loop in a network. Mesh analysis is applicable if the given network
contains voltage sources. If there exist current sources in a circuit, then it should
be converted into equivalent voltage sources.
Q-129 What is nodal analysis?
Ans Nodal analysis is one of the basic techniques used to finding solution for voltage
drop across the nodes in a given circuit. Nodal analysis is applicable if the given
network contains current sources. If there exists voltage sources in the given
circuit, then it can to be converted into equivalent current sources.
Q-130 When do we go for Supremes analysis?
Ans If the branches in the network has a current source, then it is slightly difficult to
apply mesh analysis. One way to overcome this difficulty is by applying the
Supremes technique. In this case we have to choose Supremes. A Supremes is
constituted by two adjacent loops that have common current source.
Q-131 State Maximum power transfer theorem.
Ans Power transferred from source to load will be maximum, when source resistance
is equal to load resistance looking back from its load terminals.
Q-132 Define duality.
Ans Two electrical network which are governed by the same type of equations are
called duality.
Q-133 What is transient state?
Ans If a network contains energy storage elements, with change in excitation, the
current and voltages change from one state to other state. The behaviour of the
voltage or current when it is changed from one state to another state is called
transient state.
Q-134 What is transient time?
Ans The time taken for the circuit to change from one steady state to another steady
state is called transient time.
Q-135 What is natural response?
Ans If we consider a circuit containing storage elements which are independent of
sources, the response depends upon the nature of the circuit, it is called natural
response.
Q-136 What is transient response?
Ans The storage elements deliver their energy to the resistances, hence the response
changes with time, gets saturated after sometime, and is referred to the transient
response.
Q-137 Define time constant or RL Circuit.
Ans The time taken to reach 63.2percent of final value in a RL Circuit is called the
time constant of RL circuit. Time constant (t) = L / R
Q-138 Define time constant of RC Circuit.
Ans The time taken to reach 36.8percent of initial current in an RC circuit is called
the time constant of RC circuit. Time constant (t) = RC.
Q-139 What is meant by natural frequency?
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Ans If the damping is made zero then the response oscillates with natural frequency
without any opposition, such a frequency is called natural frequency of
oscillations, denoted as (ωn)
Q-140 Define damping ratio.
Ans It is the ratio of actual resistance (R) in the circuit to the critical resistance (R
cr).It is denoted by greek letter Zeta(ξ)
Q-141 What is driving point impedance?
Ans The ratio of the Laplace transform of the voltage at the point to the Laplace
transform of the current at the same port is called driving point impedance. The
driving point impedance of the network is define as Z (S) = V(s) /I (s)
Q-142 Define resonant circuit.
Ans The circuit that treat a narrow range of frequencies very differently than all other
frequencies. These are referred to as resonant circuit. The gain of a highly
resonant circuit attains a sharp maximum or minimum as its resonant frequency.
Q-143 When the circuit is said to be in resonance?
Ans 1. A network is in resonance when the voltage and current at the network
input terminals are in phase.
2.If inductive reactance of a network equals capacitive reactance then the
network is said to be resonance
Q-144 What is resonant frequency?
Ans The frequency at which resonance occurs is called resonance frequency.
Q-145 Define bandwidth.
Ans The bandwidth (BW) is defined as the frequency difference between upper cut-
off frequency (f2) and lower cut-off frequency (f1)
Bandwidth = f2-f1
Where f2 upper cut-off frequency F1 lower cut-off frequency
Q-146 Define quality factor.
Ans The quality factor is defined as the ratio of maximum energy stored to the energy
dissipated per cycle.
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Network theory Interview & Viva

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