Chapter 1: Electricity
The objective of the module is to survey the field of electrical engineering at some (shallow) depth, history of
the electron for transmission of power and information, acquiring the jargon for communicating effectively
with engineers, understanding the underlying physics of electric & electronic circuits, and training skills in
“thinking like an engineer” by solving practical exercises.
This graph shows us the progresses that occurred during since the existence of humanity. Energy
transformation has been something since the end of the 18th century. The focus on energy transformation
ended at the end of the 20th century and information transformation became the main importance.
The industrial age happened from 1840 till 1970. During that time there were a lot of
innovations in terms of power transmission. An example of power transmission is a
lightbulb. A lightbulb works by passing electricity through a thin filament (usually
tungsten). The filament heats up due to electrical resistance until it glows, emitting
visible light. The bulb is sealed with an inert gas or vacuum to prevent the filament
from oxidizing and burning out quickly.
A. The physics of electron flow
The Black and Blue wires are needed for the flow of electrons. The black wire typically carries the live
or "hot" current, while the blue wire is neutral, completing the electrical circuit.
The Green wire is the grounding or earth wire. It provides a safety mechanism by directing unwanted
electricity safely to the ground, preventing electric shocks or fire hazards if a fault occurs.
It is important to know that a wire need to be made of a material who can transmit electricity. Such a material
is called a conductor. A conductor is at the centre of any wire and is mostly made of metal due to metal's high
conductivity. Some metals, however, are more conductive than others. Aluminium, copper, and high-strength
alloys are the main materials you'll find at the centre of your wire and cable.
The Bohr’s model of the Copper atom looks like that à
We can see how much electrons an element has by looking which element it is
on the Mendeleev periodic table. Copper is the 29th element.
Here’s how we distribute the electrons in the different shells:
1st shell (inner) can contain a maximum of 2 electrons.
2nd shell can contain a maximum of 8 electrons.
3rd shell can contain a maximum of 18 electrons.
4th shell and beyond can contain even more electrons (32 and so on).
,Electron flow in copper wires
Electrons always goes from negative (-) to positive (+). On the
other side the flow of electric current goes in opposite direction.
It goes from positive (+) to negative (-). It is important to know
that no electrons go lost during the process.
The model is an illustration of how electrons are moving during the process.
Never an electron goes lost during the process, otherwise we have a short circuit
But there are still possible reasons of loss of electrons à
If there is a default in the circuit
If someone is being electrocuted
The grounding (green wire) has the task to detect a leak and stopping the process (security mechanism)
.
When there is no power/battery linked to the wire, electrons are moving
freely and in random directions. They are moving less fast than with a battery
because of room temperature. This is the reason why metals are great
conductors, because of freely moving electrons.
The reason why a metal is a possible good conductor is because
of ‘the free valence electron’ on the last shelf of the atom. It is
easy to take that electron away of the atom.
When you put a battery, the battery makes the electrons move
in different directions. When electron A goes away from its
molecule, electron B can easily take the place of electron A
In the past we used very noble metals, like silver and copper.
Nowadays everything between conductor and isolator like
Germanium (in chips) has a lower quality but works also good
enough.
To know if an element is a great conductor, you need to look at the resistivity of the element or metal. It gives how easy an
atom will move, how strongly does the material resists to electric current. The resistivity is expressed in ‘Ohms’.
The resistance of a wire made of a specific element depends on the resistivity of that element à
Resistance is occurring because of the friction of some electrons in the wire. Those frictions cause the creation of
heat. The friction of electrons can be caused because the wire is too thin. So, a possible solution to this problem is
to have a thicker wire. Thanks to his there will be more capacity because of the bigger diameter. This causes less
friction for the electrons and because of that there less creation of heat and finally less energy is consumed.
It is also important to know that the resistivity depends on the temperature. They
are positively correlated. If one increases, the other one increases also.
When 2500 °C is reached, a steady point is attained. The resistivity will not change anymore.
When the temperature is that low (-273 °C) that there is no resistivity, we have
superconductivity.
,B. The drift speed of electrons
The drift speed of an electron is the average velocity that a free electron in a conductor (like copper wire)
attains due to an electric field.
Exercise: At what speed the electrons move inside the wire?
C. The transmission speed with electrons
On the left, a battery pumps electrons into the
wire. On the right, electrons exit. Electrons
experiences force almost instantaneously and
push each other trough the wire.
The electrons push against each other and this creates the movement
To understand the process, it is the same system as the Newton’s cradle. When one ball is
lifted and released, it strikes the next, and the impact energy travels through the stationary
balls to push the ball on the opposite end outward. The working behind this is the same as in
a wire. It is all about energy transmission.
Analogy between hydraulic and electric power
You can remember the basics of electric power by comparing it with ‘la pêche aux canards’. A pump is creating
the flow of the water. There is no leak (no drop of water is getting lost) and there is a continuous loop that goes
very slow.
When a pipe is blocked with hair, it takes a larger pressure to achieve
the same flow of water. Pushing electric current through a resistance is
like pushing water through a pipe blocked with hair.
, D. Basic formulas
Here are some basic formulas that we will use à
E. The war of currents
There are 2 types of currents à
1. Direct Current (DC)
2. Alternate current (AC)
Direct current
Direct Current has been created by Thomas Edison. When that innovation was equipped in a
room there was a plate that mentionned how people should lighten the room. This plate was
necessary because otherwise people would try to light it with matches. The electric light in a
room was a complete innovation.
This is a Dynamo machine that has been created by Edison Lighting Co.,
and this machine served 400 lamps at 82 customers.
A dynamo convert mechanical rotation into electric power. Dynamo is a
device that makes direct current electric power using
electromagnetism.
The original Dynamo machine has been created by
Zénobe Gramme. The machine that Edison created, had the same mechanism but was more
advansed in terms of efficiency and durability.
Before the creation of electro-mechanical generators, we could only create electricity thanks to piles. Piles was
the first form of public lightening. The pile has been created by Volta.
You see there the army of piles needed to make one big lightbulb lightening up. The light was
very bright, and it was the first form of public lightening.
How does the Carbon arc lamp and the dynamo machine works à
In a carbon arc lamp, the electrodes are carbon sticks in free air. To lighten the lamp, the
sticks are touched together, thus allowing a relatively low voltage to strike the arc. The
sticks are then slowly drawn apart, such that plasma is created, and electric current
heats and maintains an arc across the gap. During the jump of the electrons, friction is
happening, this creates heath and when the heath is high enough, we can see photons.
Carbon’s atoms are vaporised by high voltage, creating a bright plasma,
like thunder bolts.
The objective of the module is to survey the field of electrical engineering at some (shallow) depth, history of
the electron for transmission of power and information, acquiring the jargon for communicating effectively
with engineers, understanding the underlying physics of electric & electronic circuits, and training skills in
“thinking like an engineer” by solving practical exercises.
This graph shows us the progresses that occurred during since the existence of humanity. Energy
transformation has been something since the end of the 18th century. The focus on energy transformation
ended at the end of the 20th century and information transformation became the main importance.
The industrial age happened from 1840 till 1970. During that time there were a lot of
innovations in terms of power transmission. An example of power transmission is a
lightbulb. A lightbulb works by passing electricity through a thin filament (usually
tungsten). The filament heats up due to electrical resistance until it glows, emitting
visible light. The bulb is sealed with an inert gas or vacuum to prevent the filament
from oxidizing and burning out quickly.
A. The physics of electron flow
The Black and Blue wires are needed for the flow of electrons. The black wire typically carries the live
or "hot" current, while the blue wire is neutral, completing the electrical circuit.
The Green wire is the grounding or earth wire. It provides a safety mechanism by directing unwanted
electricity safely to the ground, preventing electric shocks or fire hazards if a fault occurs.
It is important to know that a wire need to be made of a material who can transmit electricity. Such a material
is called a conductor. A conductor is at the centre of any wire and is mostly made of metal due to metal's high
conductivity. Some metals, however, are more conductive than others. Aluminium, copper, and high-strength
alloys are the main materials you'll find at the centre of your wire and cable.
The Bohr’s model of the Copper atom looks like that à
We can see how much electrons an element has by looking which element it is
on the Mendeleev periodic table. Copper is the 29th element.
Here’s how we distribute the electrons in the different shells:
1st shell (inner) can contain a maximum of 2 electrons.
2nd shell can contain a maximum of 8 electrons.
3rd shell can contain a maximum of 18 electrons.
4th shell and beyond can contain even more electrons (32 and so on).
,Electron flow in copper wires
Electrons always goes from negative (-) to positive (+). On the
other side the flow of electric current goes in opposite direction.
It goes from positive (+) to negative (-). It is important to know
that no electrons go lost during the process.
The model is an illustration of how electrons are moving during the process.
Never an electron goes lost during the process, otherwise we have a short circuit
But there are still possible reasons of loss of electrons à
If there is a default in the circuit
If someone is being electrocuted
The grounding (green wire) has the task to detect a leak and stopping the process (security mechanism)
.
When there is no power/battery linked to the wire, electrons are moving
freely and in random directions. They are moving less fast than with a battery
because of room temperature. This is the reason why metals are great
conductors, because of freely moving electrons.
The reason why a metal is a possible good conductor is because
of ‘the free valence electron’ on the last shelf of the atom. It is
easy to take that electron away of the atom.
When you put a battery, the battery makes the electrons move
in different directions. When electron A goes away from its
molecule, electron B can easily take the place of electron A
In the past we used very noble metals, like silver and copper.
Nowadays everything between conductor and isolator like
Germanium (in chips) has a lower quality but works also good
enough.
To know if an element is a great conductor, you need to look at the resistivity of the element or metal. It gives how easy an
atom will move, how strongly does the material resists to electric current. The resistivity is expressed in ‘Ohms’.
The resistance of a wire made of a specific element depends on the resistivity of that element à
Resistance is occurring because of the friction of some electrons in the wire. Those frictions cause the creation of
heat. The friction of electrons can be caused because the wire is too thin. So, a possible solution to this problem is
to have a thicker wire. Thanks to his there will be more capacity because of the bigger diameter. This causes less
friction for the electrons and because of that there less creation of heat and finally less energy is consumed.
It is also important to know that the resistivity depends on the temperature. They
are positively correlated. If one increases, the other one increases also.
When 2500 °C is reached, a steady point is attained. The resistivity will not change anymore.
When the temperature is that low (-273 °C) that there is no resistivity, we have
superconductivity.
,B. The drift speed of electrons
The drift speed of an electron is the average velocity that a free electron in a conductor (like copper wire)
attains due to an electric field.
Exercise: At what speed the electrons move inside the wire?
C. The transmission speed with electrons
On the left, a battery pumps electrons into the
wire. On the right, electrons exit. Electrons
experiences force almost instantaneously and
push each other trough the wire.
The electrons push against each other and this creates the movement
To understand the process, it is the same system as the Newton’s cradle. When one ball is
lifted and released, it strikes the next, and the impact energy travels through the stationary
balls to push the ball on the opposite end outward. The working behind this is the same as in
a wire. It is all about energy transmission.
Analogy between hydraulic and electric power
You can remember the basics of electric power by comparing it with ‘la pêche aux canards’. A pump is creating
the flow of the water. There is no leak (no drop of water is getting lost) and there is a continuous loop that goes
very slow.
When a pipe is blocked with hair, it takes a larger pressure to achieve
the same flow of water. Pushing electric current through a resistance is
like pushing water through a pipe blocked with hair.
, D. Basic formulas
Here are some basic formulas that we will use à
E. The war of currents
There are 2 types of currents à
1. Direct Current (DC)
2. Alternate current (AC)
Direct current
Direct Current has been created by Thomas Edison. When that innovation was equipped in a
room there was a plate that mentionned how people should lighten the room. This plate was
necessary because otherwise people would try to light it with matches. The electric light in a
room was a complete innovation.
This is a Dynamo machine that has been created by Edison Lighting Co.,
and this machine served 400 lamps at 82 customers.
A dynamo convert mechanical rotation into electric power. Dynamo is a
device that makes direct current electric power using
electromagnetism.
The original Dynamo machine has been created by
Zénobe Gramme. The machine that Edison created, had the same mechanism but was more
advansed in terms of efficiency and durability.
Before the creation of electro-mechanical generators, we could only create electricity thanks to piles. Piles was
the first form of public lightening. The pile has been created by Volta.
You see there the army of piles needed to make one big lightbulb lightening up. The light was
very bright, and it was the first form of public lightening.
How does the Carbon arc lamp and the dynamo machine works à
In a carbon arc lamp, the electrodes are carbon sticks in free air. To lighten the lamp, the
sticks are touched together, thus allowing a relatively low voltage to strike the arc. The
sticks are then slowly drawn apart, such that plasma is created, and electric current
heats and maintains an arc across the gap. During the jump of the electrons, friction is
happening, this creates heath and when the heath is high enough, we can see photons.
Carbon’s atoms are vaporised by high voltage, creating a bright plasma,
like thunder bolts.
