Basics of Electricity.pptx

Basics of Electricity
by
Dheenathayalan.R.
ZRI Enterprises, Mookondapalli,Hosur – 635126
Mobile : 8124 36 4336

Objective
Definition of Electricity
Day to Day Applications
2
Dheenathayalan.R/ ZRI Enterprises/ Hosur

Definition of Electricity
Electricity is defined as the flow of electric
charge. Electricity is one type of energy.
Electricity is the movement of electrons.
Electrons create charge, which we can use to
do work.
Electricity is all around us.
Charge is a property of matter--just like
mass, volume, or density. It is measurable.
3
Dheenathayalan.R/ ZRI Enterprises/ Hosur

 Matter – Matter is a Physical Substance.
 Matter is any type of material.
 Matter is anything that has mass and takes up space.
Example – Wooden table
 All physical objects are composed of matter, in the
form of atoms, which are in turn composed of protons,
neutrons, and electrons.
 Mass is the measurement of the quantity of matter
regardless of both its location in the universe and the
gravitational force applied to it.
 SI unit(International system of Units) of Mass is
Kilogram(Kg).
Dheenathayalan.R/ ZRI Enterprises/ Hosur 4

 Weight(W)– The Weight is a force that acts at all times
on all objects .
 The Earth pulls on all objects with a force of gravity
downward toward the center of the Earth.
 W = mg where ‘m’ is mass in Kilograms(Kg),’g’ is
acceleration due to gravity in m/s².
 Unit of weight is Kg m (= 1Newton)
S²
 Gravity - the force that attracts a body towards the
centre of the earth, or towards any other physical body
having mass.
 1Kg = 9.81Newton(N)

 Speed - is the distance travelled per unit of time. It does not
have direction.(Scalar quantity)
 Unit of Speed is metres per second.(m/s)
 Velocity - is the distance travelled per unit of time in a
specific direction.(Vector quantity)
 Velocity - "the rate at which an object changes its
position.”(Speed with direction)
 Unit of Velocity is metres per second.(m/s)
 Scalars are quantities that are fully described by a
magnitude (distance or numerical value)
alone.Example:10metres
 Vectors are quantities that are fully described by both a
magnitude and a direction. Example :10metres,East.

• Acceleration - is a vector quantity that is defined as the
rate at which an object changes its velocity. An object is
accelerating if it is changing its velocity. Unit of acceleration is
m/s².

Atom - is the smallest particle of a chemical
element that can exist. Atoms are tiny.
Atoms are the building block of matter.
Building blocks of atoms: Electrons ,Protons
and Neutrons.
Each atom has a center nucleus, where the
protons and neutrons are densely packed
together. Surrounding the nucleus are a
group of orbiting electrons(in elliptical orbit).

 Protons carries
Positive charge(+).
Electron carries
Negative charge(-).
Neutron carries
No charge.

In an atom,
Number of Electron = Number of Proton
Atomic number = Number of Protons in the
nucleus of an atom.
Atomic Weight = Total number of neutron and
proton of an atom.
Electron is not considered to calculate atomic
weight due to its negligible weight.

Proton Neutron Electron
• In nucleus In nucleus Outside nucleus
• Tightly Bound Tightly Bound Weakly Bound
• Positive Charge No Charge Negative Charge
• Massive Massive Not very massive

The number of protons in an atom is
important, because it defines what chemical
element the atom represents.
Copper Atom
Name: Copper
Symbol: Cu
Atomic Number: 29
Number of Protons/Electrons: 29
Number of Neutrons: 35

Electrons are critical to the working of
electricity.
Valence
Electrons
The electrons on the outer
orbit of the atom are called
valence electrons.

The electrons on the
outer orbit of the atom are
called valence electrons.
With enough
outside force, a valence
electron can escape orbit
of the atom and become
free.
Free electrons
allow us to move charge,
which is what electricity
is all about.

 Electrostatic Force - is a force that operates
between charges.
 It states that charges of the same type repel each
other, while charges of opposite types are attracted
together.
 Opposites attract, and likes repel.

 Consider Copper wire:
 Due to electrostatic force, electrons will push away
other electrons and be attracted to protons. Thus
electrons flow(charges flow).
 With enough electrostatic force on the valence electron-
-either pushing it with another negative charge or
attracting it with a positive charge--we can eject the
electron from orbit around the atom creating a free
electron.

 Conductivity – means the ability of the material to
conduct electricity.
 Elements with high conductivity, which have very
mobile electrons, are called conductors. (Copper,
Silver, and Gold )
 Elements with low conductivity are called insulators.
(Glass, Rubber, Plastic)

• Electric Field
Field that surrounds electrically charged particles and
exerts force on all other charged particles in the field, either
attracting or repelling them.
Electric field is defined as the electric force per unit
charge.

• Electric Field
A negative charge has an inward electric field because
it attracts positive charges.
The positive charge has an outward electric field,
pushing away like charges.

• Electric Field
Electric fields can't be seen as they don't have a physical
appearance, but the effect they have is very real.
For Example , Earth's gravitational field, the effect of a
massive body attracting other bodies.
Earth's gravitational field can be modeled with a set of vectors all
pointing into the center of the planet; regardless of where you are on the
surface, you'll feel the force pushing you towards it.

Electric Field
Electrostatic Field Electrodynamic Field
Electrostatic fields are electric fields that do not change
with time. Such fields are present when systems of charged
matter are stationary, or when electric currents are unchanging.
Electrodynamic fields are electric fields which do
change with time, for instance when charges are in motion

• Electricity is the movement of electrons.
• Electrons create charge, which we can harness to do work.
• Light bulb, mobile phone, etc., are all harnessing the
movement of the electrons in order to do work. They all
operate using the same basic power source: the movement of
electrons.
• Voltage is the difference in charge between two points.
• Current is the rate at which charge is flowing.
• Resistance is a material's tendency to resist the flow of
charge (current).

Voltage:
Voltage is the amount of potential energy between two points on
a circuit.
One point has more charge than another.
The difference in charge between the two points is called
voltage.
It is measured in Volts(V).
(The unit "volt" is named after the Italian physicist Alessandro
Volta who invented what is considered the first chemical battery.)

Voltage:
Example – Water Tank
Water = Charge
Pressure = Voltage
Flow = Current

Current: Tank 1 Tank 2
Example –Two water tanks
• Think that the amount of water flowing
through outlet of the tank as current.
• For water, we will measure
the volume of the water flowing
through the outlet of tank over a certain
period of time. (Tank1>Tank2)
• For Current, we measure the amount
of charge flowing through the circuit over a
period of time.
• Current (I)is measured in Amperes.

Resistance: Tank 1 Tank 2
Example –Two water tanks
• The outlet of Tank2 is smaller than
Tank1. (Tank2outlet<Tank1outlet)
• Less water flow in Tank2
compared to Tank1.
• Resistance in Tank2 is greater than
Resistance in Tank1.
• Tank2 resistance>Tank1resistance.
• So less current flow in Tank2.

Relationship between Voltage,Current,Resistance.
• Voltage is the difference
in charge between two points.
• Current is the rate at
which charge is flowing.
• Resistance is a material's
tendency to resist the flow of
charge (current).
• Water = Charge (measured in Coulombs)
• Pressure = Voltage (measured in Volts)
• Flow = Current (measured in Amperes)
• Outlet Width = Resistance(measured in Ohms)

Ohm’s Law:
Combining the elements of voltage, current, and resistance, Ohm
developed the formula:
V = I * R
Where
• V = Voltage in volts
• I = Current in amps
• R = Resistance in ohms

Current is Directly Proportional to Voltage.
( I ∝ V )
Current is Inversely Proportional to
Resistance.
 When a voltage source is connected to a closed loop circuit the
voltage will produce a current flowing around the circuit.

Formula Wheel

Forms of Electricity
Static Electricity Current Electricity

Static Electricity:
Static electricity exists when there is a build-up of opposite
charges on objects separated by an insulator.
It is called “static” because the displaced electrons tend to
remain stationary after being moved from one insulating
material to another.

Static Electricity:
Static electricity - electric phenomenon in which charged
particles are transferred from one body to another.
For example, if two objects are rubbed together, especially if
the objects are insulators (surrounding air is dry) the objects
acquire equal and opposite charges and an attractive force
develops between them.
The object that loses electrons becomes positively charged, and
the other becomes negatively charged.
The force is simply the attraction between charges of opposite
sign.

Static Electricity
Lightening

• Current Electricity
Current electricity exists when charges are able to
constantly flow.
In static electricity(Static), charges gather and remain at
rest.
In current electricity (dynamic), charges are always on the
move.
Example :Starting a car/Bike,Turning ON light etc

Current Electricity
In order to flow,
current
electricity
requires a
circuit: a
closed, never-
ending loop of
conductive
material.

Types of Current Electricity

• Electric current flows in two ways:
Alternating current (AC) Direct current (DC).
In Alternating current, current keeps switching
directions periodically – forward and backward.
In Direct current it flows in a single direction
steadily.

• Alternating current (AC)
Electric charges flow changes its direction periodically.
Most commonly used and most preferred electric power for
household equipment, office, and buildings, etc.
Alternating current can be identified in waveform called a sine
wave. The measurement is read as Hertz or Hz

• Direct current (DC)
The flow of current in direct current does not change
periodically.
The current electricity flows in a single direction in a
steady voltage.The major use of DC is to supply power for
electrical devices and also to charge batteries. For example,
mobile phone batteries, flashlights, flat-screen television, hybrid
and electric vehicles.
Simplest way to measure
direct current (DC)
is by using a digital multimeter

Types of Alternating current (AC)

Key Differences between Single Phase and Three Phase
Supplies:
1
The definition of the single-phase power supply is, the power
supplies through a single conductor.
The definition of the three-phase power supply is, the power
flows through three conductors.
2
Single phase requires the single wire to connect the circuit
Three -phase needs three wires to connect the circuit.

Key Differences between Single Phase and Three Phase Supplies:
3
The single-phase power supply has
one distinct wave cycle .
The three phase power supply has
three distinct wave cycles.
RYB simply stands for
Red, Yellow and Blue respectively
in a three phase electrical system.

Supplies:
4
The voltage of the single phase is 230V.
The voltage of the three phase is 415V.
5
The capacity of power transfer in the single phase is
minimum.
The capacity of power transfer in the three phase is
maximum.

Supplies:
6
The connection of single phase is simple.
The connection of three phase is complicated.
7
The loss in single phase is maximum and efficiency is less.
The loss in three phase is minimum and efficiency is high.
8
The single-phase is inexpensive.
The three-phase is expensive.

Key Differences between Single Phase and Three Phase Supplies:
9
The single-phase AC power supply is utilized for home appliances.
The three phase power supply is used in huge industries to run
heavy loads.
Note:
Phase is a time gap between the voltages and mentioned in
degrees.
One cycle in AC is 360°. This is same as 0°. AC is the voltage which
changes with time. When another AC voltage has little time difference
from the first one, the gap is phase difference

More about AC and DC…
 A constant voltage source is called a DC Voltage with a voltage that
varies periodically with time is called an AC voltage.
 Voltage is measured in volts, with one volt being defined as the
electrical pressure required to force an electrical current of one
ampere through a resistance of one Ohm.
 Voltages are generally expressed in Volts with prefixes used to
denote sub multiples of the voltage such as microvolts (μV = 10−6
V ),
millivolts ( mV = 10−3V ) or kilovolts ( kV = 103V). Voltage can be
either positive or negative.
 Batteries or power supplies are mostly used to produce a steady D.C.
(direct current) voltage source such as 5v, 12v, 24v etc in electronic
circuits and systems.
 While A.C. (alternating current) voltage sources are available for
domestic house and industrial power and lighting as well as power
transmission

Electricity @ day to day applications.

What is Electrical Earthing or Grounding?
Connecting the metallic parts of electric
machinery and devices to the earth plate or earth
electrode (which is buried in the moisture earth) through
a thick conductor wire (which has very low resistance)
for safety purpose is known as Earthing or grounding.
Earthing and Grounding are the same terms used for earthing.
Grounding is the commonly word used for earthing in the North
American standards like IEEE, NEC, ANSI and UL etc while,
Earthing is used in European, Common wealth countries and
Britain standards like IS and IEC etc.

Why Earthing is Important?
The primary purpose of earthing is to avoid or minimize the
danger of electrocution, fire due to earth leakage of current through
undesired path and to ensure that the potential of a current carrying
conductor does not rise with respect to the earth than its designed
insulation.
Electrocution is death or severe injury caused by electric
shock from electric current passing through the body.
When the metallic part of electrical appliances (parts that can conduct
or allow passage of electric current) comes in contact with a live wire,
maybe due to failure of installations or failure in cable insulation, the
metal become charged and static charge accumulates on it. If a person
touches such a charged metal, the result is a severe shock.
To avoid such instances, the power supply systems and parts of
appliances have to be earthed so as to transfer the charge directly
to the earth. This is why we need Electrical Earthing or
Grounding in electrical installation systems.

Plug
Plug is a device for making an electrical
connection between an appliance and the mains,
consisting of an insulated casing with metal pins that fit
into holes in a socket.
2Pin Plug
An electrical plug that has two pins for inserting
into a socket. Live and Neutral.(No Earth pin)
3Pin Plug
An electrical plug with three pins or metal
projections to fit into a socket. Live, Neutral and Earth.

Plug
• Live wire carries electric current to the appliances.
• Neutral wire completes the circuit by forming a path for the
current back to mains.
• The earth wire is for our protection, in case the live wire
makes a contact with metal casing of an appliance. When this
happens, the current will pass to the earth instead of our body,
thus saving us.

3 Pin Plug
Why Earth Pin is Longer and Bigger in 3-Pin Plugs?

3 Pin Plug
Why it is Longer?
The earth pin should be the first to connect and the last to
disconnect with electric supply. This is why earth pin is longer
than the live and neutral pin on 3-pin plugins.
Below are the reason to do so,
When we insert a 3-pin plugin into a 3-pin socket, the
earth pin is the first to make a contact with the socket as
compared to the Live and Neutral Pins.
The earth pin is the last to disconnect from the socket
when removing the plug from the socket. i.e. Line and Neutral
disconnect first and then the earth pin.
This way, earthing is well maintained during the
operation for proper safety and protection.

3 Pin Plug
Why it is Thicker?
First reason, to prevent the wrong way to operate a 3-pin plug and
connected electrical machine for the safety purpose.
In short, the earth pin is bigger and it cannot be inserted in the
live or neutral slot of the socket even by mistake.
Second reason, for thicker pin is that the law of resistance. The
resistance is inversely proportional to the area of the conductor.
i.e. thicker of the conductor, lesser is the resistance.
Third reason, modern 3 pin wall sockets have safety shutter on the
Line and Neural lines to prevent someone (especially children) to insert
conducting materials in it which cause electric shock. In this case, the
longer earth pin help to open the shutters for Line and Neutral pins i.e.
without longer earth pin, The shutters for Line and Neutral remains
closed for better safety.

Capacitor:
Capacitors are simple passive device that can store
an electrical charge on their plates when connected to a
voltage source.
The capacitor is a component which has the ability or
“capacity” to store energy in the form of an electrical charge
producing a potential difference (Static Voltage) across its
plates, much like a small rechargeable battery.

Difference between a Battery and a Capacitor
The main difference between a battery and a
capacitor is that,
Battery stores charge in the form of
chemical energy and convert to the electrical
energy whereas,
Capacitor stores charge in the form of
electrostatic field.

Electric Motor
An electric motor is an electrical machine that converts
electrical energy into mechanical energy.

Electric Motor
Induction Motor
 Induction motor works on the principle of induction.
 When the power supply is given to the stator, it produces
rotating magnetic field which gets induced in the rotor of
induction motor causing rotor to rotate.
 As they run at Asynchronous speed they are called Asynchronous
motor.
(Induction motor works on the principle of induction where
electro-magnetic field is induced into the rotor when rotating
magnetic field of stator cuts the stationary rotor.)

Electric Motor
Synchronous motor is a machine whose rotor speed and
the speed of the stator magnetic field is equal. Synchronous
motor does not have slip.
Asynchronous motor is a machine whose rotor rotates at
the speed less than the synchronous speed. ...
AC Induction Motor is known as the Asynchronous
Motor.

Electric Motor
Slip
Slip(S) is defined as difference between Synchronous Speed
(Ns) (Speed of rotation of magnetic field) and Rotor Speed Nr
(Speed of rotatory part of induction motor).
Slip Speed = Ns – Nr
The speed of rotor cannot be equal to synchronous speed i.e.
Nr < Ns, the value of slip s is always less than one. For induction
motor, 0<s<1.

Basics of Electricity.pptx

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