Electromagnetic induction occurs when a changing magnetic field induces a current in a conductor. Magnetic flux is the measure of the magnetic field passing through an area. Faraday's law states that an electromotive force (EMF) is induced in a conductor when there is a change in magnetic flux over time. Transformers use this principle to change voltage levels using a primary and secondary coil wound around an iron core. Lenz's law describes how the induced current will flow in a direction that creates an opposing magnetic field to the changing field that created it.
Presentation on Electromagnetic Induction.
Physics two presentation of CSE dept. Southeast University.
PPTX slides made by Saleh Ibne Omar.
December 2017.
This Presentation gives a basic idea about Electromagnetic induction,Faraday's Law ,Lenz's law and the application of Electromagnetic Induction. I included some real life examples of electromagnetic induction also. I hope everyone will like it
Presentation on Electromagnetic Induction.
Physics two presentation of CSE dept. Southeast University.
PPTX slides made by Saleh Ibne Omar.
December 2017.
This Presentation gives a basic idea about Electromagnetic induction,Faraday's Law ,Lenz's law and the application of Electromagnetic Induction. I included some real life examples of electromagnetic induction also. I hope everyone will like it
basic principles of electrical machines,faraday's laws of electro magnetic induction principle.dynamically induced Emf statically induced emf applications to electrical machines
The force felt by a unit positive charge or test charge when it's kept near a charge is called Electric Field. The electric field is also defined as the region which attracts or repels a charge. The electric field is a vector quantity and it denoted by E. Copy the link given below and paste it in new browser window to get more information on Electric Field www.askiitians.com/iit-jee-electrostatics/electric-field/
Electromagnetic induction builds on the concept of magnets and magnetic fields in grade 10. Most of the work covered here is quite clear and straight forward.
basic principles of electrical machines,faraday's laws of electro magnetic induction principle.dynamically induced Emf statically induced emf applications to electrical machines
The force felt by a unit positive charge or test charge when it's kept near a charge is called Electric Field. The electric field is also defined as the region which attracts or repels a charge. The electric field is a vector quantity and it denoted by E. Copy the link given below and paste it in new browser window to get more information on Electric Field www.askiitians.com/iit-jee-electrostatics/electric-field/
Electromagnetic induction builds on the concept of magnets and magnetic fields in grade 10. Most of the work covered here is quite clear and straight forward.
A transformer is a passive electrical device that transfers electrical energy from one electrical circuit to another, or multiple circuits. A varying current in any one coil of the transformer produces a varying magnetic flux in the transformer's core
Operation “Blue Star” is the only event in the history of Independent India where the state went into war with its own people. Even after about 40 years it is not clear if it was culmination of states anger over people of the region, a political game of power or start of dictatorial chapter in the democratic setup.
The people of Punjab felt alienated from main stream due to denial of their just demands during a long democratic struggle since independence. As it happen all over the word, it led to militant struggle with great loss of lives of military, police and civilian personnel. Killing of Indira Gandhi and massacre of innocent Sikhs in Delhi and other India cities was also associated with this movement.
Students, digital devices and success - Andreas Schleicher - 27 May 2024..pptxEduSkills OECD
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Welcome to TechSoup New Member Orientation and Q&A (May 2024).pdfTechSoup
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This is a presentation by Dada Robert in a Your Skill Boost masterclass organised by the Excellence Foundation for South Sudan (EFSS) on Saturday, the 25th and Sunday, the 26th of May 2024.
He discussed the concept of quality improvement, emphasizing its applicability to various aspects of life, including personal, project, and program improvements. He defined quality as doing the right thing at the right time in the right way to achieve the best possible results and discussed the concept of the "gap" between what we know and what we do, and how this gap represents the areas we need to improve. He explained the scientific approach to quality improvement, which involves systematic performance analysis, testing and learning, and implementing change ideas. He also highlighted the importance of client focus and a team approach to quality improvement.
Model Attribute Check Company Auto PropertyCeline George
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2024.06.01 Introducing a competency framework for languag learning materials ...Sandy Millin
http://sandymillin.wordpress.com/iateflwebinar2024
Published classroom materials form the basis of syllabuses, drive teacher professional development, and have a potentially huge influence on learners, teachers and education systems. All teachers also create their own materials, whether a few sentences on a blackboard, a highly-structured fully-realised online course, or anything in between. Despite this, the knowledge and skills needed to create effective language learning materials are rarely part of teacher training, and are mostly learnt by trial and error.
Knowledge and skills frameworks, generally called competency frameworks, for ELT teachers, trainers and managers have existed for a few years now. However, until I created one for my MA dissertation, there wasn’t one drawing together what we need to know and do to be able to effectively produce language learning materials.
This webinar will introduce you to my framework, highlighting the key competencies I identified from my research. It will also show how anybody involved in language teaching (any language, not just English!), teacher training, managing schools or developing language learning materials can benefit from using the framework.
We all have good and bad thoughts from time to time and situation to situation. We are bombarded daily with spiraling thoughts(both negative and positive) creating all-consuming feel , making us difficult to manage with associated suffering. Good thoughts are like our Mob Signal (Positive thought) amidst noise(negative thought) in the atmosphere. Negative thoughts like noise outweigh positive thoughts. These thoughts often create unwanted confusion, trouble, stress and frustration in our mind as well as chaos in our physical world. Negative thoughts are also known as “distorted thinking”.
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3. Magnetic Flux
The first step to understanding the complex nature of
electromagnetic induction is to understand the idea
of magnetic flux.
Flux is a general term associated with a FIELD that is bound by a
certain AREA. So MAGNETIC FLUX is any AREA that has a
MAGNETIC FIELD passing through it.
A
B
4. Faraday’s Law
Faraday learned that if you change any part of the flux over time
you could induce a current in a conductor and thus create a
source of EMF (voltage, potential difference). Since we are
dealing with time here were a talking about the RATE of
CHANGE of FLUX, which is called Faraday’s Law.
wireofturns#
)cos(
=
∆
∆
−=
∆
∆Φ
−=
N
t
BA
N
t
N B θ
ε
5. Useful Applications
AC Generators use Faraday’s
law to produce rotation and
thus convert electrical and
magnetic energy into
rotational kinetic energy.
This idea can be used to
run all kinds of motors.
Since the current in the coil
is AC, it is turning on and
off thus creating a
CHANGING magnetic field
of its own. Its own
magnetic field interferes
with the shown magnetic
field to produce rotation.
6. Lenz’s Law
Lenz's law gives the direction of the induced emf and current
resulting from electromagnetic induction. In effect, electro
magnetically induced emf and hence the current flows in a coil or
a circuit in such a direction that the magnetic field setup by it
always opposes the cause which produces it.
t
N B
∆
∆Φ
−=εLenz’s Law
7. Inductance
The ratio of magnetic flux to current is the
inductance.
Inductance is measured in henry.
1 H = 1 T m2
/ A
More common, 1 H = 1 V / A / s
The inductance can be derived for an ideal
solenoid.
I
L
Φ
=
l
rN
l
AN
L
22
0
2
0 πµµ
==
8. Induced EMF
Faraday’s law gives the
magnitude of the induced
emf.
Depends on rate of change
The definition of inductance
gives a relationship between
voltage and current.
More useful in circuits
Inductive elements in a
circuit act like batteries.
Stabilizes current
t
M
∆
∆Φ
−=ε
t
I
L
∆
∆
−=ε
9. Self Inductance
The property of the coil due to which it opposes the change of current flowing
through it is called self inductance
Suppose that we have a coil having N turns carrying a current I
That means that there is a magnetic flux through the coil
This flux can also be written as being proportional to the current
ILN B =Φ
with L being the self inductance having the same units as the mutual inductance
10. If the current changes, then the magnetic flux through the coil will also change,
giving rise to an induced emf in the coil
This induced emf will be such as to oppose the change in the current with its
value given by
dt
dI
L−=ε
If the current I is increasing, then
If the current I is decreasing, then
Self Inductance
11. There are circuit elements that behave in this manner and they are called
inductors and they are used to oppose any change in the current in the circuit
As to how they actually affect a circuit’s behavior will be discussed shortly
Self Inductance
12. Mutual Inductance
The property of the coil due to
which it opposes the change of
current in neighboring coil is
called mutual inductance.
The definition of inductance
applies to transformers.
Mutual inductance vs self-
inductance
Mutual inductance applies to
both windings.
AV∆
AN BN
R
t
NV M
BB
∆
∆Φ
−=∆ t
I
M
t
N M
B
∆
∆
=
∆
∆Φ
−=ε
13. Transformers
A transformer is a device that changes ac electric power at
one voltage level to ac electric power at another voltage
level through the action of a magnetic field.
There are two or more stationary electric circuits that are
coupled magnetically.
It involves interchange of electric energy between two or
more electric systems
Transformers provide much needed capability of changing
the voltage and current levels easily.
They are used to step-up generator voltage to an appropriate
voltage level for power transfer.
Stepping down the transmission voltage at various levels for
distribution and power utilization.
14. Transformers
Probably one of the greatest inventions of all time is the
transformer. AC Current from the primary coil moves quickly
BACK and FORTH (thus the idea of changing!) across the
secondary coil. The moving magnetic field caused by the
changing field (flux) induces a current in the secondary coil.
If the secondary coil has MORE turns
than the primary you can step up the
voltage and runs devices that would
normally need MORE voltage than
what you have coming in. We call this
a STEP UP transformer.
We can use this idea in reverse as well
to create a STEP DOWN transformer.
15. Single-Phase Transformers
• A transformer is a magnetically operated
machine.
• All values of a transformer are proportional
to its turns ratio.
16. Single-Phase Transformers
• The primary winding is connected to the incoming
power supply.
• The secondary winding is connected to the driven
load.
• This is an isolation transformer. The secondary
winding is physically and electrically isolated from the
primary winding.
17. Working of a transformer
1. When current in the primary coil
changes being alternating in
nature, a changing magnetic field
is produced
2. This changing magnetic field gets
associated with the secondary
through the soft iron core
3. Hence magnetic flux linked with
the secondary coil changes.
4. Which induces e.m.f. in the
secondary.
19. Single-Phase Transformers
• Each set of windings (primary and secondary) is formed from loops of wire
wrapped around the core.
• Each loop of wire is called a turn.
• The ratio of the primary and secondary voltages is determined by the ratio of
the number of turns in the primary and secondary windings.
• The volts-per-turn ratio is the same on both the primary and secondary
windings.
20. Constructional detail : Shell type
• Windings are wrapped around the center leg of a
laminated core.
22. The Equivalent Circuit of a Transformer
The losses that occur in transformers have to be accounted for in any
accurate model of transformer behavior.
1. Copper (I2
R) losses. Copper losses are the resistive heating losses in the
primary and secondary windings of the transformer. They are proportional
to the square of the current in the windings.
2. Eddy current losses. Eddy current losses are resistive heating losses in
the core of the transformer. They are proportional to the square of the
voltage applied to the transformer.
3. Hysteresis losses. Hysteresis losses are associated with the
rearrangement of the magnetic domains in the core during each half-cycle.
They are a complex, nonlinear function of the voltage applied to the
transformer.
4. Leakage flux. The fluxes which escape the core and pass through only
one of the transformer windings are leakage fluxes. These escaped fluxes
produce a self-inductance in the primary and secondary coils, and the
effects of this inductance must be accounted for.
24. ECE 441 24
Voltage Regulation
% 100%
nl rated
rated
E V
reg per unit regulation
V
regulation per unit
−
= = − −
= − ×
Enl = no-load output voltage
Vrated = voltmeter reading at the output
terminals when the transformer is
supplying the rated apparent power
25. 25
When the breaker is open, no current flows in Req,LS ,
jXeq,LS , or ZLOAD,LS , therefore
Vout = VLS = E’LS = Enl
26. 26
With rated load on the secondary, E’LS = ILSZeq,LS + VLS
ILS = rated low-side current at a specified power factor
VLS = rated low-side voltage
Zeq,LS = equivalent impedance of the transformer
referred to the low-side
E’LS = no-load low-side voltage
27. Transformer Efficiency
Transformer efficiency is defined as (applies to motors, generators and
transformers):
%100×=
in
out
P
P
η
%100×
+
=
lossout
out
PP
P
η
Types of losses incurred in a transformer:
Copper I2
R losses
Hysteresis losses
Eddy current losses
Therefore, for a transformer, efficiency may be calculated using the following:
%100
cos
cos
x
IVPP
IV
SScoreCu
SS
θ
θ
η
++
=