3. CsNHS Senior High School
Caestebanan National High School
What is Electromagnetic Induction?
refers to the generation of an electric current
by passing a metal wire through a magnetic
field.
When an induced current is produced because of
voltage production (E.M.F) due to a changing
magnetic field, it is called electromagnetic induction.
4. CsNHS Senior High School
Caestebanan National High School
What is Electromagnetic Induction?
5. CsNHS Senior High School
Caestebanan National High School
Brief History of EM Induction
In 1820, Hans Christian
Oersted first discovered that
a magnetic field is always
associated with an electric
current.
6. CsNHS Senior High School
Caestebanan National High School
Brief History of EM Induction
In August 29, 1831,
Michael Faraday discovered
electromagnetic induction
by his famous induction ring
experiment.
7. CsNHS Senior High School
Caestebanan National High School
Characteristics of EM Induction
For movements between magnetic bar and the conductor, there
will be deflections in galvanometer.
If the bar and the conductor remain steady then there will be no
deflections in the galvanometer.
If the pole of the magnetic bar is changed, the direction of
induced current will change.
When the loops in the coil increases the deflection become
greater and when loops decreases the deflection become
smaller.
8. CsNHS Senior High School
Caestebanan National High School
Magnetic Flux
The flux of the magnetic field
through a surface is defined in a
similar manner as we defined flux in
the electric field.
9. CsNHS Senior High School
Caestebanan National High School
Magnetic Flux
Wb)
or Weber(
Tm
:
Unit
cos
2
BA
A
B
B
B
10. CsNHS Senior High School
Caestebanan National High School
Magnetic Flux
The SI unit of magnetic flux is the weber (Wb) (in
derived units: volt-seconds), and the CGS unit is
the Maxwell.
12. CsNHS Senior High School
Caestebanan National High School
Faraday’s Experiment on EM Induction
He used a coil of wire,
galvanometer, and a bar magnet,
by noticing deflections he
conducted his first experiment.
13. CsNHS Senior High School
Caestebanan National High School
Faraday’s Experiment on EM Induction
He replaced the magnet bar with
a current carrying solenoid to
perform his second experiment.
14. CsNHS Senior High School
Caestebanan National High School
Faraday’s Experiment on EM Induction
He placed two coils close
together face to face but at rest
with respect to each other and by
closing and opening the circuit he
conducted his third experiment.
15. CsNHS Senior High School
Caestebanan National High School
Faraday’s Experiment
16. CsNHS Senior High School
Caestebanan National High School
Faraday’s Experiment on EM Induction
wire
of
turns
#
)
cos
(
N
t
BA
N
t
N B
18. CsNHS Senior High School
Caestebanan National High School
Faraday’s Law
It states that, the E.M.F induced in a wire is
proportional to the rate of the flux through the
loop.
19. CsNHS Senior High School
Caestebanan National High School
Lenz’s Law
The induced E.M.F acts to the circulate a current in
a direction that oppose the change in flux which
caused the induced E.M.F
20. CsNHS Senior High School
Caestebanan National High School
Lenz’s Law
Lenz's law gives the direction of the induced emf and
current resulting from electromagnetic induction.
The law provides a physical interpretation of the
choice of sign in Faraday's law of induction,
indicating that the induced emf and the change in
flux have opposite signs.
21. CsNHS Senior High School
Caestebanan National High School
Lenz’s Law
t
N B
Lenz’s Law
22. CsNHS Senior High School
Caestebanan National High School
Lenz’s Law
According to Lenz’s law, the
direction of included current
in a coil is such that it always
opposes the cause which
produces it.
23. CsNHS Senior High School
Caestebanan National High School
Self-Induction
When the main current in the coil
decreases, the induced current
opposes the decay of current in
the coil.
When the main current in the coil
increases, the induced current
opposes the growth of current in
the coil.
24. CsNHS Senior High School
Caestebanan National High School
Mutual-Induction
When the main current in the coil
decreases, induced current
developed in the neighboring coil
opposes the decay of current in the
coil.
When the main current in the coil
increases, the induced current
developed in the neighboring coil
opposes the growth of current in the
coil
25. CsNHS Senior High School
Caestebanan National High School
Lenz’s Law and Faraday’s Law
t
N B
26. CsNHS Senior High School
Caestebanan National High School
Neumann’s Law
The magnitude of the induced E.M.F is
proportional to the rate of change of the magnetic
flux linking the circuit.
28. CsNHS Senior High School
Caestebanan National High School
Induction Sealing
• Induction sealing is the process
of bonding thermoplastic
materials by induction heating.
This involves controlled heating
an electrically conducting object
(usually aluminum foil)
by electromagnetic induction,
through heat generated in the
object by eddy currents.
• Induction sealing is widely used to seal
capped:
– Sauces
– Dressings
– Ketchup
– Mustard
– Seasonings
– peanut butters
– Snacks
– Nuts
– Pretzels
– Powdered drinks
– Teas
– Sports drinks
– Coffees
– Teas
– Orange juice
– Milk
29. CsNHS Senior High School
Caestebanan National High School
Induction Sealing
30. CsNHS Senior High School
Caestebanan National High School
Induction Motor
•are electric motors that use alternating current (AC),
propelled by a magnetic field that rotates. They are made
up of a rotor, a stator and coils that convert electrical
energy into mechanical energy using electromagnetic
induction.
•AC induction motors are highly efficient and flexible, and
relatively simple in design, which allows them to match
the load demand for almost any electrical application.
31. CsNHS Senior High School
Caestebanan National High School
Transformer
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.
32. CsNHS Senior High School
Caestebanan National High School
Microphone
A microphone works when sound waves
enter the filter of a microphone. Inside
the filter, a diaphragm is vibrated by the
sound waves which in turn moves a coil
of wire wrapped around a magnet. The
movement of the wire in the magnetic
field induces a current in the wire. Thus
sound waves can be turned into
electronic signals and then amplified
through a speaker.
33. CsNHS Senior High School
Caestebanan National High School
Generators
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.
34. CsNHS Senior High School
Caestebanan National High School
Wireless Charging
35. CsNHS Senior High School
Caestebanan National High School
Word Problem #1
A coil with 200 turns of wire is wrapped on an 18.0 cm square frame. Each
turn has the same area, equal to that of the frame, and the total
resistance of the coil is 2.0W . A uniform magnetic field is applied
perpendicularly to the plane of the coil. If the field changes uniformly
from 0 to 0.500 T in 0.80 s, find the magnitude of the induced emf in the
coil while the field has changed as well as the magnitude of the induced
current.
36. CsNHS Senior High School
Caestebanan National High School
Word Problem #1
I
I
IR
x
t
BA
N
t
N B
)
2
(
80
.
0
90
cos
)
18
.
0
18
.
0
)(
0
500
.
0
(
200
cos