Ch 2 fee diploma ee

1. MR.KARTIK K. PATEL
(B.E.-ELECT. ENGG.)
(LECT. IN EE DEPT.-VPMP
POLYTECHNIC)
CHAPTER NO.:-2
ELECTROMAGNETIC INDUCTION

2. TOPICS:-
INTRODUCTION
FARADAY’S LAWS OF
ELECTROMAGNETIC INDUCTION.
DYNAMICALLY INDUCED EMF
FLEMING’S RIGHT HAND RULE
STATICALLY INDUCED EMF
1. SELF INDUCED EMF
2. MUTUALLY INDUCED EMF

3. The History of
Induction:
“In 1831 Joseph Henry discovered magnetic induction.”
“ Michael Faraday's ideas about conservation of energy led
him to believe that since an electric current could cause
a magnetic field, a magnetic field should be able to
produce an electric current. He demonstrated this
principle of induction in 1831.’’
So the whole thing started 180 years ago
Joseph Henry
(1797-1878)
Michael Faraday
(1791-1867)

4. 1. INTRODUCTION:1. INTRODUCTION:
THE PHENOMENA OF ELECTROMAGNETI
INDUCTION ARE VERY IMPRTANT FOR THE
STUDY OF THE WORKING PRINCIPLE OF THE
ELECTRICAL MACHINES.
THE ELECTRICAL M/C LIKE DC
MOTOR, DC GENERATOR, INDUCTION
MOTOR, TRANSFORMER, ALTERNATOR
WORKS ON INDUCTION PRINCIPLE.

5. ELECTROMAGNETIC INDUCTION:ELECTROMAGNETIC INDUCTION:
How to Induce an EMF?
An emf can be induced whenever there is a
change in flux.

6. Relative motion between a magnet
and a coil
Conductor moving in the magnetic field

7. 2. FARADAY’S LAWS OF 2. FARADAY’S LAWS OF
ELECTROMAGNETIC INDUCTION:ELECTROMAGNETIC INDUCTION:
Michael Faraday
(1791 – 1867)

8. THERE ARE TWO LAWS OF
FARADAY’S RELATED TO
ELECTROMAGNETIC
INDUCTION AS STATED
BELOW:
FARADAY’SFARADAY’S LAWS:-LAWS:-

9. FARADAY’S FIRST LAW:-FARADAY’S FIRST LAW:-
“WHEN A CONDUCTOR CUTS THE MAGNETIC
FIELD, THE EMF INDUCED IN THAT
CONDUCTOR.’’

10. 2.FARADAY’S SECOND LAW2.FARADAY’S SECOND LAW ::
“THE MAGNITUDE OF EMF INDUCED IN ANY
CONDUCTRO IS EQUAL TO THE RATE OF
CHANGE OF FLUX LINKAGES WITH IT.”

11. FARADAY’S LAW:-
If we change the magnetic flux through a coil of N
turns, an induced emf appears in every turn and the
total emf induced in the coil is the sum of these
individual induced emfs.

12. FFaraday’s Law for a Single araday’s Law for a Single
LoopLoop::
dt
d
E
F
-=e=

13. Faraday’s Law for a coil Faraday’s Law for a coil
having N turnshaving N turns::
dt
d
NE
F
-=e=

14. Examples of Induced Current:-
Any change of current in primary
induces a current in secondary.

15. Bar magnet moves through coil
Current induced in coil v
S N
Reverse pole
Induced current changes sign
v
N S
Coil moves past fixed bar magnet
Current induced in coil S N
Bar magnet stationary inside coil
No current induced in coil
N S
Direction of Induced Current

16. 3. TYPES OF INDUCED EMF:-3. TYPES OF INDUCED EMF:-
THERE ARE TWO TYPES OF INDUCED EMF:-
1.DYNAMICALLY INDUCED EMF
2.STATICALLY INDUCED EMF
SELF INDUCED EMF
MUTUALLY INDUCED EMF

17. 3.1 DYNAMICALLY INDUCED EMF:3.1 DYNAMICALLY INDUCED EMF:
Definition:-
“The EMF Induced in the coil due to the
physical movement of the magnetic field
or coil is known as Dynamically Induced
EMF.”

18. Consider a conductor A of length L meters placed in
uniform magnetic field of flux density B wb/ m
2

area =l*dx
flux difference=Bldx
E=Bldx / dt
But velocity,
V =dx/dt
So ,
E=Blv volt.
E=Blv*sinO

19.  CONDITIONS FOR PRODUCTION
OF DYNAMICALLY INDUCED EMF:-
• FOLLOWING THREE CONDITION :-FOLLOWING THREE CONDITION :-
•Presents of magnetic fields
•Presents of conductor
•Relative movement of magnetic field and conductor

20. 2) Statically induced Emf:-2) Statically induced Emf:-
Definition:-
“ There is no physical motion of conductor but due the flux,
the flux link with the coil is changed and so emf induced in
the coil. This emf is called statically induced emf.”
There are two types of statically induced EMF:-
1)Self induced emf
2)Mutually induced emf

21. 1) Self induced EMF:-1) Self induced EMF:-
Definition:- “ The emf induced in the coil due
to change its own flux linked with is known
as self induced emf.”
-Conductor remains stationary and flux
linked with it is changed. (the current which
creates the flux changes i.e increases or
decreases).
-

22. Consider a coil having N turns as shown in fig, when the current
flowing through is, a flux will produced in the iron core. So the
flux link with coil changes from its initial value of F
1
to final
value of

F2 wb in time t second.

23.  self inductance:-self inductance:-
“ The property of the coil oppose the change in current or flux is
called self inductance.”
Co-efficient of self inductance:-
“The co-efficient of self inductance is defined as the ratio of flux
link with the coil to the current flow in coil.”
It is denoted by L.
Its unit is Henry (H).

24. Consider a coil having N turns. When the current I
flowing through it, it will produced the flux.
Hence the co-efficient of self inducance is given by,
B(t)
~
i
L
I
B
º
F
L
dIdt
º-
e
(/)
dt
di
L-=e
VnAnL
oo
22
mm == 

25. 2) Mutually induced EMF:-2) Mutually induced EMF:-
“ The emf induced in one coil due to the change in flux of anther
coil linked with it. Is called mutually induced emf.”
if current changes in coil #1, an emf is induced in coil #2
1
2e
F
=-
d
N
dt
F µ B
B µ I
1

rewrite as:
1
2e=-
dI
M
dt
M is the “mutual inductance”

26. 2) Mutual induction:-2) Mutual induction:-
“ The property of the coil to produce the emf in
anther coil placed nearer to them when the current
flowing through the first coil changes is known as the
mutual inductance.
•It is denoted by M.
•Its unit is Henry(H).

29. Compare the dynamically Compare the dynamically
induced emf with statically induced emf with statically
induced emf:-induced emf:-
Dynamically emf:
“the emf induced in the coil
due to physical movement
of the magnetic field or coil
is called dyamically emf.
E=Blv sino volt
In this type of emf there is
physical motion of
conductor.
Example: alternator, d.c
generator.
Statically emf:
“ the emf induced in coil
due to the flux linked with
the coil changes is called
statically emf.”

In this type of emf there is
no any physical motion of
conductor.
Example:- induction
motor, transformer.

30. Thanks all of
you….