There is no coherent formal definition which can be given for electricity that states ‘this is what electricity is’. In actuality it is a property of the physical world that is intrinsically present and which is examined and exploited instead of explained. Most attempts to describe it centre on its behaviour and its effects instead of its existence that must simply be accepted as part of nature. In electronic and electrical engineering it is essentially a source of energy that can be generated and transformed into other forms of energy like mechanical energy to do work or employed in its own right in electronic circuits to process electrical signals that usually signify information in some form or other. For more information, kindly visit: Expertsminds
1
Electrical Engineering
DC Circuit Analysis
Lecture: The Nature of Electricity
Introduction
There is no coherent formal definition which can be given for electricity that states ‘this is what
electricity is’. In actuality it is a property of the physical world that is intrinsically present and
which is examined and exploited instead of explained. Most attempts to describe it centre on its
behaviour and its effects instead of its existence that must simply be accepted as part of nature. In
electronic and electrical engineering it is essentially a source of energy that can be generated and
transformed into other forms of energy like mechanical energy to do work or employed in its own
right in electronic circuits to process electrical signals that usually signify information in some form
or other.
Atoms:
All materials in physical world, both synthetic and natural, are made up of atoms. Our present
knowledge and representation of the atom is mainly based on the work of Niels Bohr (1885-1962) a
Danish physicist and Nobel Prize winner, whose model of atom is that of a nucleus at the centre as
shown in figure below, surrounded by orbiting electrons. The three-dimensional orbits are
categorized in groups termed as shells. The nucleus consists of two types of particle that
collectively account for the weight of atom. The first of such is the neutron that possesses the
property of weight however is neutral in the electrical respect in that, it possesses no electrical
charge. Second is the proton that has similar weight as the neutron, however also possesses an
electric charge that is nominated as positive by convention. The particles orbiting around the
nucleus are electrons, and such have negligible mass as compared with the protons, but contain an
equivalent and opposite charge which is nominated as negative. The atoms in their natural state
have similar number of protons and electrons and are thus electrically neutral.
Electrons orbiting the nucleus acquire energy and as well rotate on their own axes while circling the
nucleus in their orbits. This energy is different in different orbits situated at differing distances from
the nucleus. At most two electrons in the same atom can encompass the same energy. Two electrons
can engage the same orbit however when they do so they spin on their own axes in the opposite
directions.
Individual atoms contain differing atomic numbers that is essentially the number of both protons
and electrons which they hold. The Periodic Table, shown in table below, lists the known atoms in
an ordered way according to different properties however primarily according to their atomic
number.
2
Figure: The Bohr Model of the Atom
Electric Charge:
Electric charge is a phenomenon related with the particles in atoms. The particle is considered to
encompass an electric charge whenever it reacts to the influence of electricity, like an electric field
or the existence of other charged particles. The protons and electrons in atoms possess the property
of charge with protons nominated as containing positive charge and electrons nominated as
containing negative charge. A French physicist Charles de Coulomb (1736 – 1806), discovered
most of the elementary laws of electrostatics that govern the behaviour of fixed charges. Among
such are the law:
“Like charges repel each other whereas unlike charges attract each other”
Unit of the charge is Coulomb, termed after him and given the symbol, C.
The magnitude of an elemental charge on a single electron or proton is given the symbol q so that:
Charge on Proton q = +1.6 x 10 -19 C ; Charge on Electron -q = -1.6 x 10 -19 C
The quantity of charge at certain point in an electrical circuit is generally designated by the symbol
Q and hence:
Electric Charge = Q Coulombs (C)
3
Table: Periodic Table of the Elements
4
5
The charged bodies experience forces among them. When both bodies encompass similar type of
charge, then the force is one of repulsion tending to attempt to move the bodies away from each
other, when they are free to move. When the bodies encompass opposite types of charge, then force
is one of attraction, tending to try to move the bodies nearer together. This is this force of attraction
between electrons and protons which holds atoms altogether. The force F between two bodies
having charges Q1 and Q2 and separated by a distance r is given by the Coulomb’s Law as:
Coulomb’s Law F = Ke [(Q1Q2)r
2] N
Here ke = 8.98 x 10
9 Nm2/C2 is termed as Coulomb’s force constant. The positive force is one of
repulsion between the charges whereas a negative force is one of attraction. Figure below shows the
lines of force between particles containing like and unlike charges. In case of like charges it can be
seen that, the forces tend to divert the charges away from each other, were they are free to move,
whereas in the case of unlike charges they would tend to shift towards each other.
Figure: The Forces between Like and Unlike Charged Particles
6
Energy Bands:
The electrons orbiting nucleus in an atom as well possess thermal energy, once the atom is at an
ambient temperature bigger than the absolute temperature of 0OK. The energy that electrons can
possess is quantised and can only contain certain permitted values. The energy possessed by an
electron is as well determined by the radius at which the orbit it occupies lies from the nucleus of
atom. As explained, only two electrons in an atom can comprise similar energy however in this
case, spin on their own axes in the opposite direction. This is termed as Pauli’s Exclusion Principle
in that; it excludes any two electrons in the same atom from having exactly similar energy features.
This as well applies when atoms are in close proximity to each other as in molecules forming up a
piece of material made from specific element. This signifies that corresponding electrons in closely
neighbouring atoms should have slightly distinct energy levels. Whenever neighbouring atoms over
a range of some hundreds of atoms are examined all of the corresponding electrons contain minute
differences in the energy levels they inhabit. This gives mount to bands of energy levels instead of
individual discrete shells, where each band is basically a continuum of energy levels extending over
a finite range. In the discussion of solids, the outermost band of an element that comprises electrons
at absolute zero temperature is termed to as the valence band and it is in this band, the electrons that
partake in most chemical interactions inhabit. The next outer band that is free of electrons at
absolute zero temperature is termed to as the conduction band. In certain materials, at temperatures
higher than absolute zero, various electrons gain sufficient energy to be able to make a transition
from the valence band to conduction band.
Figure below shows a representation of energy bands in materials of three various types namely:
insulators, conductors and the semi-conductors. Insulators are characterised by a big energy gap
between the valence and conduction bands. This signifies that at room temperature no electrons
gain adequate energy to make a transition between bands and hence electrons remain firmly bonded
to their atoms in valence band.
In case of conductors it can be seen that the valence and conduction bands overlap. This signifies
that there is an abundant supply of free energy levels close to those engaged by electrons in the
upper area of the valence band of metals. At room temperature electrons can simply move into the
vacant levels in the conduction band. With this abundant supply of vacant energy levels to move
between the external electrons of metals essentially break free of their parent atoms and become
free charge carriers each containing the change –q defined formerly. Such free negatively-charged
electrons can then simply be made to move beneath the influence of an electric field for instance.
Popular materials employed as conductors in electrical equipment and wiring are: Copper (Cu),
Silver (Ag), Nickel (Ni), Aluminium (Al), Gold (Au) and Iron (Fe). Lead (Pb) is one of the main
components of solder which when melted is employed to join wires together electrically.
Semiconductors encompass an energy gap between the valence and conduction bands which is
much lower than that of the insulators. As a result, at room temperature, a number of electrons can
make the transition from valence band to the conduction band however this number is much smaller
than from the case of conductors. The extent of conduction in semi-conductors can be controlled by
doping the semi-conductor materials with impurities in the form of the other element from a
neighbouring group in the Periodic Table. This procedure is employed in most active electronic
devices and forms the basis of semiconductor industry. The most general semiconductors are
Germanium (Ge) and Silicon (Si).
7
Figure: Energy Bands in Solid Materials
Potential and Voltage:
In the world, we live in ground, which is normally taken as somewhere deep in the earth, is
considered as electrically neutral point to which all electrical consequences can be referenced. In
realism, it can be argued that this point is really somewhere in the deep outer-space. Though,
ground serves as a suitable reference to be considered as electrical ‘zero’ point. Anything which is
electrically joined to ground is taken to be at zero potential. When a body has a quantity of positive
charge present on it someway, like the proton in an atom, it has a potential that is higher than
ground and is stated to be at a positive potential relative to ground. When a body consists of a
quantity of negative charge, like the electron in an atom, it is stated to be at negative a potential
relative to ground. It has been seen above that, forces exist between charged particles and forces are
always related with energy or the ability to do work. When like-charged particles in close proximity
are free to move, then the forces which exist between them will cause them to move away from one
another. This is an indication which charge or a potential other than ‘zero’ or ‘ground’ is
intrinsically related with energy. It is expressed in terms of voltage where this is essentially the
energy per unit of electric charge.
Voltage = (Energy/Charge) volts (V) or 1 Volt = 1 Joule/1 Coulomb
Much often and particularly in the field of Electronic Engineering, the words voltage and potential
are treated as interchangeable and both are evaluated in units of Volts named after an Italian
physicist Alessandro Volta (1745-1827), who discovered electrolysis and also discovered the
battery.
When two points have distinct voltages or potentials relative to ground such that one point is at a
potential V1 whereas the other is at a potential V2, then we can define potential difference V
8
between the two points as simply the difference among the two voltages or potentials as measured
relative to ground. The potential difference will thus as well have units of Volts.
Potential difference V = V1 – V2 Volts
Potential Difference is specified as positive whenever the potential V1 relative to ground is more
positive or less negative than potential V2 relative to ground. Thus, in practice, it can be either
negative or positive depending on the polarities and magnitudes of the potentials V1 and V2.
Electric Field and Electromotive Force:
Whenever forces exist among bodies, the energy related with such forces is considered to act in a
field. In case of forces related with charged particles or bodies the energy gives mount to an electric
field. The lines of force among charged particles shown in Figure above essentially show the
direction of electric field that exists between such charges by virtue of their electric potentials. The
electric field can be seen as acting from a point of positive potential in the direction of a point of
negative potential as shown by the direction of field lines. The electric field is thus thought of as
acting all along a path. Its strength based on the magnitudes of the potentials among which it acts
and the distance among the points at which such potentials are positioned so that:
m
V
d
V
ce
Dis
Difference
Potential
E
Strength
Field
Electric
/
tan
=
=
→
Whenever an electric field acts all along a path where charged particles are free to move it give
increase to an influence on the mobile charge carriers termed as an electromotive force or emf. This
force is not strictly the Newtonian physical or mechanical force but instead an electrical one and is
really measured in Volts just as is the potential difference that gives rise to it. The electromotive
force in an electric circuit should come from some source of electrical energy like a battery. The
voltage between the terminals of battery is essentially the emf that it generates.
Current:
The energy bands shown in figure of energy bands of materials above for conductors point out
overlap between the conduction and valence bands. In good conductors, there is an abundant supply
of free energy levels in the conduction band and electrons at room temperature can simply make the
energy transition to such free levels and can then move between adjacent atoms with easiness.
Whenever charged particles which are free to move are positioned in an electric field, they
experience an electromotive force as an outcome of the field. If an emf or electric field is applied
across a piece of material that is made up of an element which is a good conductor, this will give
mount to a continual flux of charged particles via the conductor as shown in figure below. This
comprises a flow of electric current. The quantity of this mobile charge passing via a unit area of
the material per unit time is termed to as the charge flux density, J.
9
Figure: Charge Flux Density in Conducting Material
Thus, not only the quantity of charge that flows, however as well the rate at which it flows via a
conductor is of significance in determining the total electric current. The Electric current is defined
as the quantity of charge flowing via a piece of conducting material per unit time and is evaluated in
units of Amperes, named after the French physicist Andre-Marie Ampere (1775 - 1836). This unit is
usually shortened to Amps in Electrical Engineering. When a quantity of charge, Q, flows via the
conductor in a time, T, then the resultant current is given as:
Current = Charge/Time I = Q/T Amperes (A)
The quantity of charge and direction of flux mainly depend on the strength and direction of electric
field, magnitude and polarity of the charge on particles. In case of electricity and electric circuits the
mobile particles that contribute to the current flow are electrons that are negatively charged.
Unluckily, in the discoveries of Physics of 17th, 18th and 19th centuries most of the conventions
concerning polarity and direction were already established prior to this was recognized. The
direction on an electric filed is taken as acting from the point of more positive to that of more
negative (or least positive) potential (that is, from plus to minus). Therefore, electrons being
negatively charged particles flow in the direction opposite to that of electric field. Though, the
direction of current flow is always particular as being in the direction of electric field. This is
sometimes termed to as the direction of conventional current. The other basic principle of electric
current is that it should always flow in a loop or circuit, therefore the term electric circuit. This is
illustrated in figure shown below.
A
uniform
cross
sectional
area
charge flux density
J
flux of charge
through material
conducting
material
10
Figure: An Illustration of an Electric Circuit
This illustrates the electric circuit comprised of a battery and a light bulb. The battery gives the emf
and the resultant electric field acts from its positive terminal in the direction towards its negative
terminal and therefore around the loop made by the battery, conducting wire and light bulb inserted
into this loop in between the sections of wire. It can be seen that the conventional current is taken as
flowing in a clockwise direction around circuit, whereas in reality electrons are really travelling in
the opposite anti-clockwise direction.
For more information, kindly visit: https://www.expertsminds.com/
Direction of
Conventional
Current
Direction of
Electric Field
Current Flow in
Loop or Circuit
Electrical Engineering
DC Circuit Analysis
Lecture: The Nature of Electricity
Introduction
There is no coherent formal definition which can be given for electricity that states ‘this is what
electricity is’. In actuality it is a property of the physical world that is intrinsically present and
which is examined and exploited instead of explained. Most attempts to describe it centre on its
behaviour and its effects instead of its existence that must simply be accepted as part of nature. In
electronic and electrical engineering it is essentially a source of energy that can be generated and
transformed into other forms of energy like mechanical energy to do work or employed in its own
right in electronic circuits to process electrical signals that usually signify information in some form
or other.
Atoms:
All materials in physical world, both synthetic and natural, are made up of atoms. Our present
knowledge and representation of the atom is mainly based on the work of Niels Bohr (1885-1962) a
Danish physicist and Nobel Prize winner, whose model of atom is that of a nucleus at the centre as
shown in figure below, surrounded by orbiting electrons. The three-dimensional orbits are
categorized in groups termed as shells. The nucleus consists of two types of particle that
collectively account for the weight of atom. The first of such is the neutron that possesses the
property of weight however is neutral in the electrical respect in that, it possesses no electrical
charge. Second is the proton that has similar weight as the neutron, however also possesses an
electric charge that is nominated as positive by convention. The particles orbiting around the
nucleus are electrons, and such have negligible mass as compared with the protons, but contain an
equivalent and opposite charge which is nominated as negative. The atoms in their natural state
have similar number of protons and electrons and are thus electrically neutral.
Electrons orbiting the nucleus acquire energy and as well rotate on their own axes while circling the
nucleus in their orbits. This energy is different in different orbits situated at differing distances from
the nucleus. At most two electrons in the same atom can encompass the same energy. Two electrons
can engage the same orbit however when they do so they spin on their own axes in the opposite
directions.
Individual atoms contain differing atomic numbers that is essentially the number of both protons
and electrons which they hold. The Periodic Table, shown in table below, lists the known atoms in
an ordered way according to different properties however primarily according to their atomic
number.
2
Figure: The Bohr Model of the Atom
Electric Charge:
Electric charge is a phenomenon related with the particles in atoms. The particle is considered to
encompass an electric charge whenever it reacts to the influence of electricity, like an electric field
or the existence of other charged particles. The protons and electrons in atoms possess the property
of charge with protons nominated as containing positive charge and electrons nominated as
containing negative charge. A French physicist Charles de Coulomb (1736 – 1806), discovered
most of the elementary laws of electrostatics that govern the behaviour of fixed charges. Among
such are the law:
“Like charges repel each other whereas unlike charges attract each other”
Unit of the charge is Coulomb, termed after him and given the symbol, C.
The magnitude of an elemental charge on a single electron or proton is given the symbol q so that:
Charge on Proton q = +1.6 x 10 -19 C ; Charge on Electron -q = -1.6 x 10 -19 C
The quantity of charge at certain point in an electrical circuit is generally designated by the symbol
Q and hence:
Electric Charge = Q Coulombs (C)
3
Table: Periodic Table of the Elements
4
5
The charged bodies experience forces among them. When both bodies encompass similar type of
charge, then the force is one of repulsion tending to attempt to move the bodies away from each
other, when they are free to move. When the bodies encompass opposite types of charge, then force
is one of attraction, tending to try to move the bodies nearer together. This is this force of attraction
between electrons and protons which holds atoms altogether. The force F between two bodies
having charges Q1 and Q2 and separated by a distance r is given by the Coulomb’s Law as:
Coulomb’s Law F = Ke [(Q1Q2)r
2] N
Here ke = 8.98 x 10
9 Nm2/C2 is termed as Coulomb’s force constant. The positive force is one of
repulsion between the charges whereas a negative force is one of attraction. Figure below shows the
lines of force between particles containing like and unlike charges. In case of like charges it can be
seen that, the forces tend to divert the charges away from each other, were they are free to move,
whereas in the case of unlike charges they would tend to shift towards each other.
Figure: The Forces between Like and Unlike Charged Particles
6
Energy Bands:
The electrons orbiting nucleus in an atom as well possess thermal energy, once the atom is at an
ambient temperature bigger than the absolute temperature of 0OK. The energy that electrons can
possess is quantised and can only contain certain permitted values. The energy possessed by an
electron is as well determined by the radius at which the orbit it occupies lies from the nucleus of
atom. As explained, only two electrons in an atom can comprise similar energy however in this
case, spin on their own axes in the opposite direction. This is termed as Pauli’s Exclusion Principle
in that; it excludes any two electrons in the same atom from having exactly similar energy features.
This as well applies when atoms are in close proximity to each other as in molecules forming up a
piece of material made from specific element. This signifies that corresponding electrons in closely
neighbouring atoms should have slightly distinct energy levels. Whenever neighbouring atoms over
a range of some hundreds of atoms are examined all of the corresponding electrons contain minute
differences in the energy levels they inhabit. This gives mount to bands of energy levels instead of
individual discrete shells, where each band is basically a continuum of energy levels extending over
a finite range. In the discussion of solids, the outermost band of an element that comprises electrons
at absolute zero temperature is termed to as the valence band and it is in this band, the electrons that
partake in most chemical interactions inhabit. The next outer band that is free of electrons at
absolute zero temperature is termed to as the conduction band. In certain materials, at temperatures
higher than absolute zero, various electrons gain sufficient energy to be able to make a transition
from the valence band to conduction band.
Figure below shows a representation of energy bands in materials of three various types namely:
insulators, conductors and the semi-conductors. Insulators are characterised by a big energy gap
between the valence and conduction bands. This signifies that at room temperature no electrons
gain adequate energy to make a transition between bands and hence electrons remain firmly bonded
to their atoms in valence band.
In case of conductors it can be seen that the valence and conduction bands overlap. This signifies
that there is an abundant supply of free energy levels close to those engaged by electrons in the
upper area of the valence band of metals. At room temperature electrons can simply move into the
vacant levels in the conduction band. With this abundant supply of vacant energy levels to move
between the external electrons of metals essentially break free of their parent atoms and become
free charge carriers each containing the change –q defined formerly. Such free negatively-charged
electrons can then simply be made to move beneath the influence of an electric field for instance.
Popular materials employed as conductors in electrical equipment and wiring are: Copper (Cu),
Silver (Ag), Nickel (Ni), Aluminium (Al), Gold (Au) and Iron (Fe). Lead (Pb) is one of the main
components of solder which when melted is employed to join wires together electrically.
Semiconductors encompass an energy gap between the valence and conduction bands which is
much lower than that of the insulators. As a result, at room temperature, a number of electrons can
make the transition from valence band to the conduction band however this number is much smaller
than from the case of conductors. The extent of conduction in semi-conductors can be controlled by
doping the semi-conductor materials with impurities in the form of the other element from a
neighbouring group in the Periodic Table. This procedure is employed in most active electronic
devices and forms the basis of semiconductor industry. The most general semiconductors are
Germanium (Ge) and Silicon (Si).
7
Figure: Energy Bands in Solid Materials
Potential and Voltage:
In the world, we live in ground, which is normally taken as somewhere deep in the earth, is
considered as electrically neutral point to which all electrical consequences can be referenced. In
realism, it can be argued that this point is really somewhere in the deep outer-space. Though,
ground serves as a suitable reference to be considered as electrical ‘zero’ point. Anything which is
electrically joined to ground is taken to be at zero potential. When a body has a quantity of positive
charge present on it someway, like the proton in an atom, it has a potential that is higher than
ground and is stated to be at a positive potential relative to ground. When a body consists of a
quantity of negative charge, like the electron in an atom, it is stated to be at negative a potential
relative to ground. It has been seen above that, forces exist between charged particles and forces are
always related with energy or the ability to do work. When like-charged particles in close proximity
are free to move, then the forces which exist between them will cause them to move away from one
another. This is an indication which charge or a potential other than ‘zero’ or ‘ground’ is
intrinsically related with energy. It is expressed in terms of voltage where this is essentially the
energy per unit of electric charge.
Voltage = (Energy/Charge) volts (V) or 1 Volt = 1 Joule/1 Coulomb
Much often and particularly in the field of Electronic Engineering, the words voltage and potential
are treated as interchangeable and both are evaluated in units of Volts named after an Italian
physicist Alessandro Volta (1745-1827), who discovered electrolysis and also discovered the
battery.
When two points have distinct voltages or potentials relative to ground such that one point is at a
potential V1 whereas the other is at a potential V2, then we can define potential difference V
8
between the two points as simply the difference among the two voltages or potentials as measured
relative to ground. The potential difference will thus as well have units of Volts.
Potential difference V = V1 – V2 Volts
Potential Difference is specified as positive whenever the potential V1 relative to ground is more
positive or less negative than potential V2 relative to ground. Thus, in practice, it can be either
negative or positive depending on the polarities and magnitudes of the potentials V1 and V2.
Electric Field and Electromotive Force:
Whenever forces exist among bodies, the energy related with such forces is considered to act in a
field. In case of forces related with charged particles or bodies the energy gives mount to an electric
field. The lines of force among charged particles shown in Figure above essentially show the
direction of electric field that exists between such charges by virtue of their electric potentials. The
electric field can be seen as acting from a point of positive potential in the direction of a point of
negative potential as shown by the direction of field lines. The electric field is thus thought of as
acting all along a path. Its strength based on the magnitudes of the potentials among which it acts
and the distance among the points at which such potentials are positioned so that:
m
V
d
V
ce
Dis
Difference
Potential
E
Strength
Field
Electric
/
tan
=
=
→
Whenever an electric field acts all along a path where charged particles are free to move it give
increase to an influence on the mobile charge carriers termed as an electromotive force or emf. This
force is not strictly the Newtonian physical or mechanical force but instead an electrical one and is
really measured in Volts just as is the potential difference that gives rise to it. The electromotive
force in an electric circuit should come from some source of electrical energy like a battery. The
voltage between the terminals of battery is essentially the emf that it generates.
Current:
The energy bands shown in figure of energy bands of materials above for conductors point out
overlap between the conduction and valence bands. In good conductors, there is an abundant supply
of free energy levels in the conduction band and electrons at room temperature can simply make the
energy transition to such free levels and can then move between adjacent atoms with easiness.
Whenever charged particles which are free to move are positioned in an electric field, they
experience an electromotive force as an outcome of the field. If an emf or electric field is applied
across a piece of material that is made up of an element which is a good conductor, this will give
mount to a continual flux of charged particles via the conductor as shown in figure below. This
comprises a flow of electric current. The quantity of this mobile charge passing via a unit area of
the material per unit time is termed to as the charge flux density, J.
9
Figure: Charge Flux Density in Conducting Material
Thus, not only the quantity of charge that flows, however as well the rate at which it flows via a
conductor is of significance in determining the total electric current. The Electric current is defined
as the quantity of charge flowing via a piece of conducting material per unit time and is evaluated in
units of Amperes, named after the French physicist Andre-Marie Ampere (1775 - 1836). This unit is
usually shortened to Amps in Electrical Engineering. When a quantity of charge, Q, flows via the
conductor in a time, T, then the resultant current is given as:
Current = Charge/Time I = Q/T Amperes (A)
The quantity of charge and direction of flux mainly depend on the strength and direction of electric
field, magnitude and polarity of the charge on particles. In case of electricity and electric circuits the
mobile particles that contribute to the current flow are electrons that are negatively charged.
Unluckily, in the discoveries of Physics of 17th, 18th and 19th centuries most of the conventions
concerning polarity and direction were already established prior to this was recognized. The
direction on an electric filed is taken as acting from the point of more positive to that of more
negative (or least positive) potential (that is, from plus to minus). Therefore, electrons being
negatively charged particles flow in the direction opposite to that of electric field. Though, the
direction of current flow is always particular as being in the direction of electric field. This is
sometimes termed to as the direction of conventional current. The other basic principle of electric
current is that it should always flow in a loop or circuit, therefore the term electric circuit. This is
illustrated in figure shown below.
A
uniform
cross
sectional
area
charge flux density
J
flux of charge
through material
conducting
material
10
Figure: An Illustration of an Electric Circuit
This illustrates the electric circuit comprised of a battery and a light bulb. The battery gives the emf
and the resultant electric field acts from its positive terminal in the direction towards its negative
terminal and therefore around the loop made by the battery, conducting wire and light bulb inserted
into this loop in between the sections of wire. It can be seen that the conventional current is taken as
flowing in a clockwise direction around circuit, whereas in reality electrons are really travelling in
the opposite anti-clockwise direction.
For more information, kindly visit: https://www.expertsminds.com/
Direction of
Conventional
Current
Direction of
Electric Field
Current Flow in
Loop or Circuit