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

1. A PowerPoint Presentation by
Akram Habib
© 2014AH

2. Electromagnetic Induction
Electromagnetic Induction is the process of
using magnetic fields to produce voltage,
and in a complete circuit, a current.
Michael Faraday first discovered it, using
some of the works of Hans Christian
Oersted. His work started at first using
different combinations of wires and
magnetic strengths and currents, but it
wasn't until he tried moving the wires that
he got any success

3. Electromagnetic Induction
Almost 200 years ago, Faraday looked for
evidence that a magnetic field would induce
an electric current with this apparatus

4. He found no evidence when the magnet was
steady, but did see a current induced when
the magnet moves up and down .

5. Electromagnetic Induction
Faraday’s Law

6. Electromagnetic Induction
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.



N B # turns of wire
( cos )



 

 
N
t
BA
N
t

7. Electromagnetic Induction
Faraday’s Law
d 
t
( )
dt
t
 ( )
 
In order to understand Faraday’s law we
need to understand the concept of
magnetic flux.
m 
r
B  d
r
 A

8. Electromagnetic Induction
Magnetic Flux:
Magnetic flux is the quantity of magnetic field that penetrates an
area at right angles to it.
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
We generally define an AREA vector as one that is perpendicular
to the surface of the material. Therefore, you can see in the figure
that the AREA vector and the Magnetic Field vector are
PARALLEL. This then produces a DOT PRODUCT between the
2 variables that then define flux.

9. Electromagnetic Induction
Lenz’s Law
The direction of the emf and thus the current is given
by Lenz’s law. The statement in bold in the center of
page 789 is a statement of Lenz’s law. Use this to find
the direction of the current. If you are looking down on
the loop from above, is the current flowing clockwise or
counter clockwise?

10. Electromagnetic Induction
Lenz’s Law
The magnetic is moving away
from the coil so the magnetic
field is decreasing, thus the
current is in a direction to off-set
the decrease.
The magnetic is moving
toward the coil so the magnetic
field is increasing, thus the
current is in a direction to off-set
the increase.

11. Electromagnetic Induction
Problem
A circular wire loop with a radius of 20 cm. is in
a constant magnetic field of 0.5 T .
What is the flux through
the loop if the normal to
the loop makes an angle
of 300 with the magnetic
field?
0
normal
300
   
t B dA B d A B dA m
 
( ) | | cos | | cos30
       
0 2 0 2
B r T m
cos30  0.5 cos30 
(0.2 )
  

12. Electromagnetic Induction
In summary
Faraday’s Law is basically used to find the
MAGNITUDE of the induced EMF. The magnitude of
the current can then be found using Ohm’s Law
provided we know the conductor’s resistance.
Lenz’s Law is part of Faraday’s Law and can help you
determine the direction of the current provided you
know HOW the flux is changing

13. Electromagnetic Induction
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.

14. Electromagnetic Induction
Transformers work only if the current is
changing; this is one reason why electricity is
transmitted as AC.

15. Electromagnetic Induction
An Induction Stove
The water in the metal pot is boiling. Yet, the water
in the glass pot is not boiling, and the stove top is
cool to the touch. The stove operates in this way
by using electromagnetic induction.

16. Electromagnetic Induction
How is a credit card reader related to
magnetism?
Magnetic data storage encodes information in a pattern of
alternating magnetic fields. When these fields move past a
small pick-up coil, the changing magnetic field creates an
induced current in the coil. This current is amplified into a
sequence of voltage pulses that represent the 0s and 1s of
digital data.