A detailed presentation explaining the principles of electromagnetism. It covers the fundamental laws given by Faraday regarding electromagnetic induction.
2. Group
Members
• Ghazi Zain Ul Abidin
• Khawaja Sinan Aamir
• Hasnain Ali Shaikh
• Hilal Haider
• Huzaifa Rehman
• Ismail Ibrahim
• Jawad Ahmed
• Mehmood
4. Revision Of Concepts
• Magnetic Flux
Measurement of the total magnetic field lines which passes through a given area
• Magnetic Flux Density
Magnetic flux density(B) is defined as the force acting per unit current per unit length on a wire placed at right angles to
the magnetic field or Region in which a moving charge experiences a force provided that the charge is not moving parallel
to the field lines
• Current
Stream of charged particles, such as electrons or ions, moving through an electrical conductor or space.
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5. Faraday’s Law of Induction describes how an
electric current can produce magnetic field and,
conversely, how a changing magnetic field can
generate electric current in a conductor. English
physicist Michael Faraday discovered magnetic
induction in 1830; however, an American
physicist, Joseph Henry is also known for his
independent efforts on same discovery according
to the University of Texas.
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6. Experiment
• The discovery of
electromagnetic induction was
based on series of experiments
carried out by Faraday
• In this experiment, Faraday
takes a magnet and a coil
and connects a galvanometer
across the coil
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7. Experiment
The result showed the following behavior
Position Of Magnet Deflection Of Galvanometer
Magnet At Rest No deflection in galvanometer
The magnet move towards the coil Deflection In galvanometer in one direction
The magnet is held stationery at the same position (near coil) No deflection in galvanometer
The magnet move away from the coil Deflection In galvanometer in opposite direction
The magnet held stationery at the same position (away from the coil) No deflection in galvanometer
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8. First Law
From The experiment he stated
"A changing magnetic field induced an
electromotive force in a conductor"
Whenever a conductor is placed in a varying
magnetic field, an electromotive force is induced.
Likewise, if the conductor circuit is closed, a current is
induced, which is called induced current
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9. Causes Of
Induction
The experiment showed that
the induction can be introduced
by;
• moving a magnet towards or
away from the coil
• moving the coil into or out of
the magnetic field
• changing the area of a coil
placed in the magnetic field
• rotating the coil relative to
the magnet
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10. Second Law
He further stated his second law as
"The induced voltage in a circuit is proportional to
the rate of change over time of the magnetic flux
through that circuit."
Mathematically
EMF = −NΔΦ/Δt
The negative sign shows that the direction of induced
emf is such that it opposes the change in flux
The direction of induced emf is given by Lenz’s law,
"An induced electric current flows in a direction such
that the current opposes the change that induced
it."
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11. Derivation
Consider a magnet approaching towards a coil. Consider two-time instances T1 and T2.
Flux linkage with the coil at the time T1 is given by
T1 = NΦ1
Flux linkage with the coil at the time T2 is given by
T2 = NΦ2
Change in the flux linkage is given by
N(Φ2 – Φ1)
Let us consider this change in flux as
Φ = Φ2 – Φ1
Hence, the change in flux linkage is given by
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12. Derivation
NΦ
The rate of change of flux linkage is given by
NΦ/t
Taking the derivative of the above equation, we get
N dΦ/dt
According to Faraday’s second law of electromagnetic induction, we know that the induced emf in a coil is equal to
the rate of change of flux linkage. Therefore,
E=Ndϕ/dt
Considering Lenz’s law,
E=−Ndϕ/dt
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13. Second Law
The derived formula shows
that the induction can
be changed by;
• changing the number of
turns in the coil i.e., N
• changing magnetic field
strength i.e., B
• changing the speed of the
relative motion between
the coil and the magnet
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14. Applications
Faraday law is one of the most basic and important
laws of electromagnetism. This law finds its
application in most of the electrical machines,
industries, and the medical field, etc.
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15. Transformer
Transformer is a device used in power transmission
of electric energy
There are two coils primary and
secondary on the transformer core. The core
laminations are joined in the form of strips. The two
coils have high mutual inductance. When
an alternating current pass through the primary coil
it creates a varying magnetic flux. As per Faraday’s
law, this change in magnetic flux induces an
EMF (electromotive force) in the secondary
coil which is linked to the core having a primary coil.
There are two types of transformers, step up and
step down.
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16. Induction
Cooker
The Induction cooker is the
fastest way of cooking. It
also works on the principle of
mutual induction. When
current flows through the coil
of copper wire placed below a
cooking container, it produces
a changing magnetic field.
This alternating or changing
magnetic field induces an emf
and hence the current in the
conductive container due to
which heat is produced.
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17. Seismometer
A device used for the measurement and
detection of earthquake is called seismometer.
This kind of seismometer works on the principle
of electromagnetic induction. It transforms
received vibrational energy into an
electrical voltage. During earthquake, the
relative motion between a magnet and a coil
induces an emf in the coil that is proportional to
the velocity of the relative’s motion. The
magnitude of emf is also proportional to
the strength of the magnet used and the
number of turns in the coil.
In practice either the magnet or the coil can be
attached to the inertial mass (in commercial
systems the magnet is itself often used as
the inertial mass).
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18. Electricity Generator
AC generator converts mechanical energy
into electrical energy. Its input supply is
mechanical energy and outputs alternating
electrical power in the form of alternating
voltage and current.
The armature rotates between the poles of
the magnet upon an axis perpendicular to
the magnetic field, the flux which links with
the armature changes continuously. An emf
is induced in the armature which produces
a current through the slip rings and brushes.
The galvanometer swings between the
positive and negative values. This indicates
that there is an alternating current flowing
through the galvanometer.
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19. Current Clamp &
Wireless Charging
• A current clamp measures electric current flowing
through a wire, cable, busbar, or other conductor
without cutting the wire through electromagnetic
induction.
• Wireless charging works by transferring energy
from the charger to a receiver in the back of the
phone via electromagnet.
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