This document describes principles of electromagnetic induction and various experiments conducted by Michael Faraday. It explains Faraday's law of induction and Lenz's law. It then discusses the working principles of AC generators and transformers. AC generators produce alternating current using a coil rotating in a magnetic field with slip rings. Transformers use the principle of electromagnetic induction to change voltage levels using a primary and secondary coil around an iron core, with different turn ratios determining voltage increase or decrease.
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.
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
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.
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
basic principles of electrical machines,faraday's laws of electro magnetic induction principle.dynamically induced Emf statically induced emf applications to electrical machines
in these notes, you will learn the basic terminologies related to magnetism or magnetic effects.
Magnetism is the most important branch in the phase of physics.
I explained it properly in these notes
Detection of Radioactivity
Characteristics of the Three Types of Emission
Nuclear Reactions
Half-Life
Uses of Radioactive Isotopes Including Safety Precautions
June 3, 2024 Anti-Semitism Letter Sent to MIT President Kornbluth and MIT Cor...Levi Shapiro
Letter from the Congress of the United States regarding Anti-Semitism sent June 3rd to MIT President Sally Kornbluth, MIT Corp Chair, Mark Gorenberg
Dear Dr. Kornbluth and Mr. Gorenberg,
The US House of Representatives is deeply concerned by ongoing and pervasive acts of antisemitic
harassment and intimidation at the Massachusetts Institute of Technology (MIT). Failing to act decisively to ensure a safe learning environment for all students would be a grave dereliction of your responsibilities as President of MIT and Chair of the MIT Corporation.
This Congress will not stand idly by and allow an environment hostile to Jewish students to persist. The House believes that your institution is in violation of Title VI of the Civil Rights Act, and the inability or
unwillingness to rectify this violation through action requires accountability.
Postsecondary education is a unique opportunity for students to learn and have their ideas and beliefs challenged. However, universities receiving hundreds of millions of federal funds annually have denied
students that opportunity and have been hijacked to become venues for the promotion of terrorism, antisemitic harassment and intimidation, unlawful encampments, and in some cases, assaults and riots.
The House of Representatives will not countenance the use of federal funds to indoctrinate students into hateful, antisemitic, anti-American supporters of terrorism. Investigations into campus antisemitism by the Committee on Education and the Workforce and the Committee on Ways and Means have been expanded into a Congress-wide probe across all relevant jurisdictions to address this national crisis. The undersigned Committees will conduct oversight into the use of federal funds at MIT and its learning environment under authorities granted to each Committee.
• The Committee on Education and the Workforce has been investigating your institution since December 7, 2023. The Committee has broad jurisdiction over postsecondary education, including its compliance with Title VI of the Civil Rights Act, campus safety concerns over disruptions to the learning environment, and the awarding of federal student aid under the Higher Education Act.
• The Committee on Oversight and Accountability is investigating the sources of funding and other support flowing to groups espousing pro-Hamas propaganda and engaged in antisemitic harassment and intimidation of students. The Committee on Oversight and Accountability is the principal oversight committee of the US House of Representatives and has broad authority to investigate “any matter” at “any time” under House Rule X.
• The Committee on Ways and Means has been investigating several universities since November 15, 2023, when the Committee held a hearing entitled From Ivory Towers to Dark Corners: Investigating the Nexus Between Antisemitism, Tax-Exempt Universities, and Terror Financing. The Committee followed the hearing with letters to those institutions on January 10, 202
Embracing GenAI - A Strategic ImperativePeter Windle
Artificial Intelligence (AI) technologies such as Generative AI, Image Generators and Large Language Models have had a dramatic impact on teaching, learning and assessment over the past 18 months. The most immediate threat AI posed was to Academic Integrity with Higher Education Institutes (HEIs) focusing their efforts on combating the use of GenAI in assessment. Guidelines were developed for staff and students, policies put in place too. Innovative educators have forged paths in the use of Generative AI for teaching, learning and assessments leading to pockets of transformation springing up across HEIs, often with little or no top-down guidance, support or direction.
This Gasta posits a strategic approach to integrating AI into HEIs to prepare staff, students and the curriculum for an evolving world and workplace. We will highlight the advantages of working with these technologies beyond the realm of teaching, learning and assessment by considering prompt engineering skills, industry impact, curriculum changes, and the need for staff upskilling. In contrast, not engaging strategically with Generative AI poses risks, including falling behind peers, missed opportunities and failing to ensure our graduates remain employable. The rapid evolution of AI technologies necessitates a proactive and strategic approach if we are to remain relevant.
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.
Model Attribute Check Company Auto PropertyCeline George
In Odoo, the multi-company feature allows you to manage multiple companies within a single Odoo database instance. Each company can have its own configurations while still sharing common resources such as products, customers, and suppliers.
Francesca Gottschalk - How can education support child empowerment.pptxEduSkills OECD
Francesca Gottschalk from the OECD’s Centre for Educational Research and Innovation presents at the Ask an Expert Webinar: How can education support child empowerment?
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.
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How to Make a Field invisible in Odoo 17Celine George
It is possible to hide or invisible some fields in odoo. Commonly using “invisible” attribute in the field definition to invisible the fields. This slide will show how to make a field invisible in odoo 17.
1. P R I N C I P L E S O F E L E C T R O M A G N E T I C I N D U C T I O N
T H E A . C . G E N E R A T O R
T H E T R A N S F O R M E R
Electromagnetic Induction
1
Electromagnetic Induction
2. D E S C R I B E A N E X P E R I M E N T W H I C H S H O W S T H A T
A C H A N G I N G M A G N E T I C F I E L D C A N I N D U C E A N
E . M . F . I N A C I R C U I T .
Electromagnetic Induction
2
Principles of Electromagnetic
Induction
3. Faraday’s Experiment
Electromagnetic Induction
3
Michael Faraday showed that electricity can be
obtained from magnetism.
The current produced in this way is called an
induced current.
The process by which the current is obtained is called
electromagnetic induction.
8. Electromagnetic Induction
8
Whenever there was a relative movement between
magnet and coil, there was induced current.
The current was induced in the circuit as a result of
the wire being cut by magnetic flux lines when either
the magnet or coil moved.
An electromotive force is induced whenever there is
a changing magnetic flux in a circuit.
9. S T A T E T H E F A C T O R S A F F E C T I N G T H E
M A G N I T U D E O F T H E I N D U C E D E . M . F .
Electromagnetic Induction
9
Principles of Electromagnetic
Induction
10. Electromagnetic Induction
10
Faraday’s law of electromagnetic induction states
that the magnitude of the induced e.m.f. is
proportional to the rate of change of the magnetic
flux linked with the circuit or rate at which the
magnetic flux are cut.
Faraday also found that the magnitude of the
induced current increases when
The magnet is move at a faster speed in and out of the coil;
A stronger magnet is used;
The number of turns in the coil is increased.
11. S T A T E T H A T T H E D I R E C T I O N O F A C U R R E N T
P R O D U C E D B Y A N I N D U C E D E . M . F . O P P O S E S T H E
C H A N G E P R O D U C I N G I T
( L E N Z ’ S L A W ) A N D D E S C R I B E H O W T H I S L A W
M A Y B E D E M O N S T R A T E D .
Electromagnetic Induction
11
Principles of Electromagnetic
Induction
12. Direction of Induced E.m.f.
Electromagnetic Induction
12
Lenz’s law of electromagnetic induction states that
the induced current is always in a direction to oppose
the change producing it.
14. D E S C R I B E A S I M P L E F O R M O F A . C . G E N E R A T O R
( R O T A T I N G C O I L O R R O T A T I N G M A G N E T ) A N D
T H E U S E O F S L I P R I N G S W H E R E
N E E D E D .
Electromagnetic Induction
14
The A.C. Generator
15. The A.C Generator
Electromagnetic Induction
15
In motor, electrical energy is used to rotate the coil
to provide mechanical energy
In generators, mechanical energy is used to rotate
the coil to produce electrical energy
Power stations use generators to supply the needed
electrical energy
A generator can be described as an electromagnetic
device which converts mechanical energy to
electrical energy
16. Principle of A.C. Generators
Electromagnetic Induction
16
A simple alternating current generator consists of a
rectangular coil mounted on an axle which is fixed
between the poles of a permanent magnet.
17. Electromagnetic Induction
17
• Using Fleming’s right-hand
rule, the induced current
flows form A to B and C to D
• The current then flows
through the two slip-rings
(X and Y) to an electrical
load.
• The two slip-rings each
make sliding contact with a
fixed carbon brush (P and
Q). The current flows from
Y to Q and from P to X.
18. Electromagnetic Induction
18
• When the coil has rotated at
180° (vertical position), the
sides of the coil will changed
places.
• The current flows from B to A
and D to C in the coil, and from
X to P and from Q to Y through
the sliding contact.
• Every time the coil turns
through 180°, the current
reverse its direction through
the electrical load.
19. Electromagnetic Induction
19
The generator produces alternating current because
slip rings are used in place of a split - ring commutator.
The slip rings keep a continuous connection
with the wire around the armature.
20. S K E T C H A G R A P H O F V O L T A G E O U T P U T A G A I N S T
T I M E F O R A S I M P L E A . C . G E N E R A T O R .
Electromagnetic Induction
20
The A.C. Generator
21. Voltage output of an A.C Generator
Electromagnetic Induction
21
• When the coil is horizontal, the rate at which the coil cuts
the magnetic lines of force is the greatest – the induced
e.m.f is maximum
• When the coil is vertical, the rate at which the coil cuts the
magnetic lines of force is the least – the induced e.m.f is
minimum
22. Electromagnetic Induction
22
• If the speed of rotation of the coil is doubled, both the
frequency of the alternating current and the rate of cutting
of the magnetic lines of force will be doubled.
• Hence the maximum output voltage is also doubled.
23. Electromagnetic Induction
23
When the number of turned of the coil is doubled, both the
frequency of the output voltage is the same although its
maximum output voltage is doubled.
24. Electromagnetic Induction
24
In conclusion, the induced electromotive force of a
generator can be increased by
Increasing the speed of rotation of the coil,
Increasing the number of turns in the coil,
Winding the coil on a soft iron core so as to concentrate the
magnetic lines of force through the coil,
Using stronger magnets
25. D E S C R I B E T H E S T R U C T U R E A N D P R I N C I P L E O F
O P E R A T I O N O F A S I M P L E I R O N - C O R E D
T R A N S F O R M E R .
Electromagnetic Induction
25
The Transformer
26. The Transformer
Electromagnetic Induction
26
• In 1831, Faraday performed an experiment by winding two coils
round a soft iron ring
• When the switch was closed, the needle of the compass which
was placed above wire XY had deflected
• The compass needle again deflected when the switch was opened
• No deflection occurred when a steady current was supplied in
coil A
27. Electromagnetic Induction
27
A transformer needs
an alternating current that will
create a changing magnetic
field.
The primary coil is connected to an
AC supply.
An alternating current passes
through a primary coil wrapped
around a soft iron core.
The changing current produces a
changing magnetic field.
This induces an alternating voltage in
the secondary coil.
This induces an alternating current
(AC) in the circuit connected to the
secondary coil.
28. Electromagnetic Induction
28
A transformer is used to change the voltage of an
alternating current.
This is done by having different numbers of turns in
the primary and secondary coils.
A step-up transformer has more turns in the
secondary coil than in the primary coil. This
increases the output voltage.
A step-down transformer decreases the voltage by
having fewer turns in the secondary coil than in the
primary coil.
29. Electromagnetic Induction
29
It may be shown that for an ideal transformer,
coilprimaryinturnsofno.
coilsecondaryinturnsofno.
ageinput voltprimary
tageoutput volsecondary
p
s
p
s
N
N
V
V
30. Electromagnetic Induction
30
From the principle of conservation of energy, the
output power cannot be more than the input power
Energy output cannot be more than energy input.
For an ideal transformer,
powerInputpowerOutput
PPSS IVIV
31. Problem Solving
Electromagnetic Induction
31
1. Calculate the output voltage from a transformer
when the input voltage is 230 V and the number of
turns on the primary coil is 2000 and the number
of turns on the secondary is 100.
2. To step down the a.c. voltage of 240 V to 12 V, what
must be the number of turns in the secondary coil,
if the primary coil has 200 turns? In this step-down
transformer, what will be the current in the
secondary coil, if the input current in the primary
coil is 5 A? Assume that the transformer is an ideal
one.
32. Electromagnetic Induction
32
3. A transformer has the ability to change an a.c.
supply of 2 kW, 240 V to 60 V.
a) What is the turns ratio of this transformer?
b) How large is the output current if the transformer is 100%
efficient?
c) What will the output current be if there is a 10% power loss in
the transformer?
4. A transformer has 500 turns in the primary and
3000 turns in the secondary. In the primary, the
potential difference is 120 V a.c. and the current is
150 mA. Find (a) the secondary potential difference
and (b) the secondary current.
33. Electromagnetic Induction
33
5. A large power transformer converts 325 000 V to 7
500 V, at the rate of 2.5 million watts. Find (a) the
primary current, (b) the secondary current.
6. A transformer has an input voltage of 2 V. There
are 50 turns on the primary coil. The secondary coil
has 600 turns.
a) What is the output voltage
b) The secondary coil has a resistance of 12 . What is the
secondary current?
c) The transformer is perfectly efficient. What is the primary
current.
34. Electromagnetic Induction
34
7. The main supply of 240 V is stepped down to 6 V using
a transformer.
a) What is the ratio of the number of turns in the secondary coil to
that in the primary coil?
b) If the number of turns in the primary coil is 1000, how many turns
are there in the secondary coil?
c) The output from the secondary coil is used to light a 6 V lamp. If
the current in the lamp is 1.5 A and the transformer is 100%
efficient, what is the current in the primary coil?
8. A step-down transformer has 1000 turns in the primary
coil and 500 turns in the secondary coil. The primary
coil is connected to a 240 V a.c. supply. If the
transformer is 100% efficient and primary current is 1.2
A, what will be the secondary current.
35. S T A T E T H E A D V A N T A G E S O F H I G H V O L T A G E
T R A N S M I S S I O N .
Electromagnetic Induction
35
The Transformer
36. D I S C U S S T H E E N V I R O N M E N T A L A N D C O S T
I M P L I C A T I O N S O F U N D E R G R O U N D P O W E R
T R A N S M I S S I O N C O M P A R E D T O
O V E R H E A D L I N E S .
Electromagnetic Induction
36
The Transformer
42. The Power Plant
Electromagnetic Induction
42
AC has at least three advantages over DC in a power
distribution grid:
Large electrical generators happen to generate AC naturally.
Transformers must have alternating current to operate.
It is easy to convert AC to DC but expensive to convert DC to
AC.
43. Electromagnetic Induction
43
Disadvantage of underground cable.
It costs five to 15 times more to install transmission lines
underground.
Underground power lines are more costly to repair. In
addition, it generally takes longer to repair than overhead lines
due to the difficulty in reaching the underground problem.
Electrical lines pass over wetlands and fragile ecosystems and
it becomes easier to avoid injury to those areas when the lines
are overhead as opposed to digging up trenches to bury
electrical lines.
44. Electromagnetic Induction
44
Power loss due to the heating effect of current in the
grid cables – heat loss given by I2R.
To reduce this is to use a very thick cable although it is heavy
and uneconomical.
Another way to reduce is by stepping up the voltage by using a
transformer.
45. Electromagnetic Induction
45
1. A magnet is suspended from a spring so that it can
move freely inside a coil which is connected to a
sensitive centre-zero ammeter.
46. Electromagnetic Induction
46
1. What does the ammeter show when the magnet
vibrates slowly up and down?
A. a reading constantly changing from left to right and right to
left
B. a steady reading to the left
C. a steady reading to the right
D. a steady zero reading
47. Electromagnetic Induction
47
2. The e.m.f. induced in a conductor moving at right-
angles to a magnetic field does not depend upon
A. the length of the conductor.
B. the resistance of the conductor.
C. the speed of the conductor.
D. the strength of the magnetic field.
49. Electromagnetic Induction
49
1. The magnet is then pulled out quickly from the
same end of the coil.
2. What happens to the direction and the size of the
current?
B
51. Electromagnetic Induction
51
1. In which direction does the induced e.m.f. make
the coil move?
A. away from the magnet
B. towards the magnet
C. downwards
D. upwards
52. Electromagnetic Induction
52
5. The wire XY shown in the diagram is connected to
a sensitive voltmeter with a centre zero. XY is then
moved quickly once through the magnetic field.
53. Electromagnetic Induction
53
1. What is observed on the voltmeter?
A. The needle moves briefly in one direction and then returns to
the centre.
B. The needle moves quickly in one direction and stays
deflected.
C. The needle vibrates rapidly from side to side whilst XY is
moving.
D. The needle stays still.
54. Electromagnetic Induction
54
6. Which parts of an a.c. generator slide past each
other when the generator is working?
A. brushes and coil
B. coil and magnets
C. magnets and slip rings
D. slip rings and brushes
56. Electromagnetic Induction
56
1. Which statement is correct?
A. The direction of the potential difference across the load
resistor is always the same.
B. The size of the induced e.m.f. depends on the number of
turns in the coil.
C. The size of the induced e.m.f. does not change as the coil
turns.
D. Winding the coil on a soft-iron cylinder makes no difference
to the induced e.m.f.
58. Electromagnetic Induction
58
1. Some changes are made, one at a time.
The speed of the drive is changed.
The strength of the magnets is changed.
The number of turns in the coil is changed.
The value of the resistor is changed.
2. How many of these alter the value of the e.m.f.
generated in the coil?
A. 1
B. 2
C. 3
D. 4
59. Electromagnetic Induction
59
9. A cathode-ray oscilloscope is connected to an a.c.
generator.
10. A wave is seen on the screen of the oscilloscope.
66. Electromagnetic Induction
66
1. Which statement is correct?
A. The input voltage is d.c.
B. The input voltage is greater than the output voltage.
C. The input voltage is less than the output voltage.
D. The input voltage is the same as the output voltage.
71. Electromagnetic Induction
71
15. A transformer has 50 turns on its primary coil and
100 turns on its secondary coil. An alternating
voltage of 25.0 V is connected across the primary
coil.
74. Electromagnetic Induction
74
1. What is the potential difference across the
secondary coil of the transformer?
A. 30 V
B. 120 V
C. 240 V
D. 480 V
75. Electromagnetic Induction
75
17. A transformer has 15 000 turns on its primary coil
and 750 turns on its secondary coil.
18. Connected in this way, for what purpose could this
transformer be used?
A. to convert the 8000 V a.c. output of a power station to 160
000 V for long-distance power transmission
B. to convert the 160 000 V d.c. supply from a power line to
8000 V for local power transmission
C. to use a 12 V d.c. supply to operate a 240 V razor
D. to use a 240 V a.c. mains supply to operate a 12 V motor
78. Electromagnetic Induction
78
19. Why is electrical energy usually transmitted at high
voltage?
A. As little energy as possible is wasted in the transmission
cables.
B. The current in the transmission cables is as large as possible.
C. The resistance of the transmission cables is as small as
possible.
D. The transmission system does not require transformers.
79. Electromagnetic Induction
79
20. Electric power cables transmit electrical energy
over large distances using a high voltage,
alternating current.
21. What are the advantages of using a high voltage
and of using an alternating current?
D