Q.
No
Detail
Chapter No. (1)
1 Marks Question
1
Define 1) EMF 2)Current
 EMF: Electromotive force is an energy transfer to an electric circuit per unit of electric charge,
volts.
 EMF=Joules/Coulombs
 Current: It is define as flow of electrons in electrical circuit and its unit is Amp.
2
measured in
Define 1) Resistance 2) conductance.
 Resistor: It oppose the flow of current and its unit is ohms.
 Resistance of circuit=Voltage/Current
 Conductance: Conductance is the measure of how easy it is for electric current to flow through something.
Conductance is symbolized by the letter “G” Conductance is the inverse of resistance: G = 1/R. Conductance is
measured in units of Siemens or mhos.
3
List Factors affecting resistance.
1)
2)
3)
4)
4
Length of the conductor
Area of cross-section of the conductor
Nature of material
Temperature
State the any four types of switches with their application.
1. Toggle Switch:
 Application: Used in household appliances
2. Push Button Switch:
 Application: Found in industrial control panels
3. Rocker Switch:
4. Application: Used in automotive applications
5. Slide Switch:
 Application: Commonly found in small electronic devices.
5
Define 1) work 2) potential difference.
 Electric Work: the work done by a battery in moving the electron in an electric circuit represents electric work.
Electrical Work=Force * Displacement
 Potential difference :It is defined as voltage difference between any two point. Current is only flow through
circuit if there is potential difference between two points.
6
Define 1) Inductor 2)Capacitor
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Inductor : It oppose the rate of change of current and its unit is Henry.
It also useful in store electrical energy inside it.
Capacitor : It oppose the rate of change of voltage and its unit is Ferad.
It also useful in store electrical energy inside it.
4 Marks Question
1
How Alternating EMF is generated?
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2
Magnetic Field: A magnetic field is required to induce the EMF. This can be created using a permanent
magnet or an electromagnet.
Conductor: A conductor, typically in the form of a wire coil, is placed in the magnetic field. The conductor
can be made of materials with high electrical conductivity, such as copper or aluminum.
Relative Motion: The conductor is either moved through the magnetic field or the magnetic field is varied
around the conductor. This relative motion between the conductor and the magnetic field is essential for
inducing the EMF.
When the relative motion occurs, the magnetic field lines passing through the conductor change, resulting in
a change in the magnetic flux. This change in magnetic flux induces an EMF, or voltage, across the ends of
the conductor according to Faraday's law.
The induced EMF is alternating in nature because the polarity and magnitude of the induced voltage change
with time. As the conductor moves or the magnetic field changes, the induced voltage alternates between
positive and negative values.
State the types of switch.
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Electrical switches: These work under the influence of semiconductors
Mechanical switches: These require manual contact with the switch for operation and are classified into
various types depending upon the poles.
3
Explain ohm's law with limitations.
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Ohm’s law states the relationship between electric current and potential difference.
The current that flows through most conductors is directly proportional to the voltage applied to it.
Ohm’s law states that the voltage across a conductor is directly proportional to the current flowing through it,
provided all physical conditions and temperatures remain constant.
Ohm’s law Limitation:
 It is only applicable for linear devices that means not applicable in non-linear devices like diode.
 Ohm’s law is not followed by semi-conductor materials like Germanium and Silicon.
4
Explain Types of Temperature Coefficient of Resistance with graph.
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Positive Temperature Coefficient of Resistance
The resistivity and the resistance of the material increase due to a decrease in τ. Hence, the value of the
temperature coefficient of metal is positive.
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Negative Temperature Coefficient of Resistance
In the case of semiconductors and insulators, the number of charge carriers per unit volume increases with an
increase in temperature. The decrease in τ is compensated well by the increase in n such that the value of
resistivity and resistance decreases with an increase in temperature.
Explain Types of Electrical Materials.
5
 Conductors: Conductors are materials that allow the flow of electric current with minimal
resistance. Copper and aluminum are widely used conductors due to their high electrical
conductivity.
 Insulators: Insulators are materials that prevent or limit the flow of electric current. They have high
resistivity, which inhibits the movement of electrons. Examples of insulating materials include
rubber, plastic, glass, and ceramic.
 Semiconductors: Semiconductors have electrical conductivity between that of conductors and
insulators. They can be controlled to conduct or block current, making them essential in electronic
devices. Silicon and germanium are commonly used semiconductors.
7 Marks Question
1
Explain with figure relation between line value and phase value
for star connection and delta connection.
2
 Delta Connection:
 Vline=Vphase;
 While Iline= √3× Iphase.
 Star Connection:
 Vline= √3 × Vphase ;
While Iline = Iphase.
Explain KCL and KVL in details.
KCL(Kirchhoff's Current Law):
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The total current entering a junction or a node is equal to the total current leaving to the node or junction.
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Example 1: Let us consider a network of assumed directions of the current as shown below.
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Example 2: Using KCL to determine the value of the unknown current i in the circuit below.
KVL(Kirchhoff's Voltage Law):
 The voltage around a loop equals the sum of every voltage drop in the same loop for any closed
network and equals zero.
3
State and explain the factors affecting the resistance.
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Resistance is that property of a conductor that opposes the flow of current through a conductor.
There are mainly four factors that affect the resistance of a conductor.
The factors that affect the resistance of a conductor are:
Length of the conductor: Resistance is directly proportional to the conductor.
Area of cross-section of the conductor: Resistance is inversely proportional to conductor
Nature of material:It depends on the nature of material used
Temperature: Resistance is directly proportional to the conductor
The factors affecting resistance are Length, Area of cross-section, Temperature, and Nature of material.
Chapter No. (2)
1 Marks Question
1
Define 1) MMF.
 MMF: Magnetomotive Force is the magnetic pressure that creates the magnetic flux in a magnetic
circuit.
 MMF: મેગ્નેટોમોટટવ ફોર્સ એ ચબ
ું કીય દબાણ છે જે ચબ
ું કીય ર્ર્કસટમાું ચુંબકીય પ્રવાહ બનાવે છે .
2
Explain Lenz's Law.
 The current induced in a loop flows in such a way so as to create a magnetic field opposite to the
direction of the field that caused it.
3
Define Permeability.
 Permeability: Magnetic permeability is defined as the ratio of the magnetic induction to the
magnetic intensity. It is a scalar quantity and is denoted by the symbol μ.
4
Define reluctance.
 Reluctance: The property of a magnetic circuit of opposing the passage of magnetic flux lines.
 Reluctance(S)=MMF/Flux
5
Define 1) magnetic flux. 2) magnetic flux density.
 Flux: Magnetic flux is a measurement of the total magnetic field which passes through a given area.
 Its unit is weber.
 Magnetic field strength: Magnetic field strength is a measure of the intensity of a magnetic field in
a given area of that field.
 Magnetic field strength(B)=Magnetic Flux/Area
6
Define 1)flux linkage.
 Flux linkage: Linkage flux is the flux that link to the magnetic circuit.
4 Marks Question
1
Explain type of magnetic materials.
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Diamagnetic materials
Those materials that people find non-magnetic such as wood, water, gold, copper, etc.
They are not attracted to any magnetic field.
Paramagnetic materials(પેરામેગ્નેટટક ર્ામગ્રી)
Paramagnetic materials are materials that tend to get weakly magnetized in the direction of the
magnetizing field when placed in a magnetic field.
 If we remove the applied field, the materials tend to lose their magnetism.
 Ferromagnetic materials:
 Ferromagnetic materials are a certain group of substances that tend to manifest or display strong
magnetism in the direction of the field due to the application of a magnetic field.
2
Explain faradays law of electromagnetic induction.
 Faraday’s First Law of Electromagnetic Induction
 Whenever a conductor is placed in a varying magnetic field, an electromotive force is induced. If the
conductor circuit is closed, a current is induced, which is called induced current.
 Faraday’s Second Law of Electromagnetic Induction
 The induced emf in a coil is equal to the rate of change of flux linkage.
EMF=-NdØ/dt
3
Explain flemings right and left hand ruls.
 Fleming’s Hand Rule states that if we arrange our thumb, forefinger and middle finger of the righthand perpendicular to each other, then the thumb points towards the direction of the motion of the
conductor relative to the magnetic field, the forefinger points towards the direction of the magnetic
field and the middle finger points towards the direction of the induced current.
4
Explain Megnetic fringing effect with diagram.
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When the magnetic field lines pass through an air gap, they tend to bulge out (see the below figure). It is
because the magnetic field lines repel each other when passing through the air (or non-magnetic materials).
This effect is known as magnetic fringing.
7 Marks Question
1
Explain generation of 3 Phase EMF with figure.
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Three-phase power is widely used in industrial, commercial, and residential applications due to its
efficiency and balanced characteristics.
Three-phase EMF is typically generated using a device called a "generator" or an "alternator."
An alternator is a rotating machine that converts mechanical energy into electrical energy.
It consists of a rotor (rotating part) and a stator (stationary part). As the rotor rotates within the
stator, it induces voltage in the stator windings.
The generation of three-phase EMF involves creating a time-varying magnetic field that interacts
with the stator windings. This is usually achieved using the principles of electromagnetic induction.
 Rotating Magnetic Field Generation
 The rotor of the alternator is connected to a prime mover, such as a steam turbine, gas turbine, water turbine,
or internal combustion engine. When the prime mover rotates the rotor, it creates a rotating magnetic field
around the rotor.
 Stator Windings
 The stator of the alternator contains three sets of windings spaced 120 degrees apart from each other. These
windings are often referred to as "phases" and are labeled as Phase A, Phase B, and Phase C.
Electromagnetic Induction
 As the rotor's magnetic field rotates, it cuts across the stator windings, inducing a voltage in each phase.
According to Faraday's law of electromagnetic induction, a changing magnetic field induces a voltage in a
conductor (in this case, the stator windings).
 Frequency and Voltage Regulation
 The frequency of the generated EMF depends on the rotational speed of the alternator's rotor and the number
of poles in the machine.
 The magnitude of the generated EMF is influenced by factors such as the magnetic field strength, the number
of turns in the stator windings, and the speed of rotation.
2
Give comparison between electric and magnetic circuit.
Parameter
Definition
Electrical Circuit
A closed path followed by electric current is known as
electric circuit.
Magnetic Circuit
A closed path followed by
magnetic field line or magnetic flux
is known as magnetic circuit.
Circuit
quantities
In electric circuit, the major quantities associated with
the circuit are EMF, voltage, current, resistance,
capacitance and inductance, etc.
The fundamental quantities
associated with magnetic circuits
are MMF, magnetic flux,
reluctance, etc.
3
Quantity
flowing in the
circuit
The electric current is the quantity which flows in an
electric circuit.
The magnetic flux is the quantity
which flows in a magnetic circuit.
Driving force
The EMF or electromotive force is the driving force in
an electric circuit, which creates potential difference so
that current can flow in the circuit.
In case of a magnetic circuit, the
MMF or Magnetomotive force is
the driving force, which causes the
flow of magnetic flux in the core of
the magnetic circuit.
Opposition
The resistance of the electric circuit opposes the electric
current flowing in the circuit.
The reluctance of the core of
magnetic circuit opposes the flow
of magnetic flux in the circuit.
Drop
The voltage drop occurs in an electric circuit due to
resistance which is given,
Voltage Drop V=IR
MMF drop occurs in a magnetic
circuit due to reluctance of the
magnetic path which is given
by,MMFdrop=ϕ×S
Explain and give difference of magnetic field of permanent magnet and electro magnate.