Download Electromagnetic Induction

Electromagnetic
Induction
Ways of generation emf
(electromotive force)
• Chemical Reaction (batteries).
• Use of Active transducers.
e.g.. photocell or thermocouples.
• Principal of Electromagnetic Induction.
Electromagnetic Induction.
• Electromagnetic Induction is the phenomenon
of voltage induction in a conductor placed in
the magnetic field.
• The generation of emf due to Electromagnetic
Induction was first obtain by the English
scientist Michael Faraday in 1831.
Laws of Electromagnetic Induction.
• Faraday’s First law
• Faraday’s Second law
• LENZ’S Law
Faraday’s First law
• The first law states that whenever the
magnetic lines of force linking with a coil or
conductor changes
• An emf gets induced in the coil or conductor.
Faraday’s Second law
• The magnitude of induced emf is directly
proportional to the rate of change of flux
linkage.
• where flux linkage=Flux X No. of coils
Expression for the induced emf
Consider the loop shown:
d m d
dx
 Bl x  Bl
dt
dt
dt
dx
E  Blv  Bl
dt
CONCLUSION: to produce emf one should make ANY
change in a magnetic flux with time!
LENZ’S Law
The direction of the emf
induced by changing flux will
produce a current that
generates a magnetic field
opposing the flux change that
produced it.
Lenz’s Law
B, H
N
S
Iinduced
V+, V-
Lenz’s Law: emf appears and current flows that creates a
magnetic field that opposes the change – in this case an
decrease – hence the negative sign in Faraday’s Law.
Lenz’s Law
B, H
N
S
Iinduced
V-, V+
Lenz’s Law: emf appears and current flows that creates a
magnetic field that opposes the change – in this case an
increase – hence the negative sign in Faraday’s Law.
Thank you……..