2. CERTIFICATE
This is to certify that the PHYSICS project titled
‘ELECTROMAGNETIC INDUCTION’ has been
successfully completed by ________________of Class XII
in partial fulfillment of curriculum of CENTRAL BOARD
OF SECONDARYEDUCATION (CBSE) leading to the
award of annual examination of the year 2017-2018.
INTERNAL EXAMINER TEACHERIN-CHARGE
3. ACKNOWLEDGEMENT
I wish to express my
sincere gratitude to
______________________(physics
teacher). I sincerely thank Mr.
_____________(lab assistant ) for
their guidance and encouragement in
carrying out this project work. I also
wish to express my gratitude to the
officials and other staff members who
rendered their help during the period
of my project work. I also thank the
principle of Andhra Education Society
school Mrs._____________ for
providing me the opportunity to
embark on this project.
8. INTRODUCTION
Faraday's law ofinduction is a basic law of electromagnetism that predicts how a
magnetic field will interact with an electric circuit to produce an
electromotive force (EMF). It is the fundamental operating
principle of transformers, inductors, and many types of electrical
motors and generators.
Electromagnetic induction was discovered independently by Michael
Faraday and Joseph Henry in 1831; however, Faraday was the first to publish
the results of his experiments. Faraday explained electromagnetic induction
using a concept he called lines of force.These equations for electromagnetics
are extremely important since they provide a means to precisely describe
how many natural physical phenomena in our universe arise and behave. The
ability to quantitatively describe physical phenomena not only allows us to
gain a better understanding of our universe, but it also makes possible a host
of technological innovations that define modern society. Understanding
Faraday’s Law of Electromagnetic Induction can be beneficial since so many
9. technologies that improve our quality of life such as electric power generation,
Faraday’s Law has a great impact on many aspects of our lives.
Faraday’s Law is the result of the experiments of the English chemist and
physicist Michael Faraday . The concept of electromagnetic induction was
actually discovered simultaneously in 1831 by Faraday in London and Joseph
Henry, an American scientist working in New York , but Faraday is credited
for the law since he published his work first . An important aspect of the
equation that quantifies Faraday’s Law comes from the work of Heinrich Lenz,
a Russian physicist who made his contribution to Faraday’s Law, now known
as Lenz’s Law, in 1834 (Institute of Chemistry).
Faraday’s law describes electromagnetic induction, whereby an electric field
is induced, or generated, by a changing magnetic field. Before expanding
upon this description, it is necessary to develop an understanding of the
concept of fields, as well as the related concept of potentials.
10. Faraday's first experimental demonstration of electromagnetic induction
(August 29, 1831), he wrapped two wires around opposite sides of an iron
ring or "torus" (an arrangement similar to a modern toroidal transformer) to
induce current
Figure 1 Faraday's First Experiment
Some physicists have remarked that Faraday's law is a single equation
describing two different phenomena: the motional EMF generated by a
magnetic force on a moving wire (see Lorentz force), and
the transformerEMF generated by an electric force due to a changing
magnetic field (due to the Maxwell–Faraday equation). James Clerk Maxwell
drew attention to this fact in his 1861 paper On Physical Lines of Force. In the
latter half of part II of that paper, Maxwell gives a separate physical
explanation for each of the two phenomena. A reference to these two aspects
of electromagnetic induction is made in some modern textbooks.
11. THEORY
Magnetic flux:
The magnetic flux (often denoted Φ or ΦB) through a surface is the
component of the B field passing through that surface. The SI unit of
magnetic flux is the weber (Wb) (in derived units: volt-seconds), and the CGS
unit is the maxwell. Magnetic flux is usually measured with a fluxmeter, which
contains measuring coils and electronics that evaluates the change of voltage
in the measuring coils to calculate the magnetic flux.
If the magnetic field is constant, the magnetic flux passing through a surface
of vector area S is
12. where B is the magnitude of the magnetic field (the magnetic flux density)
having the unit of Wb/m2 (Tesla), S is the area of the surface, and θ is the
angle between the magnetic field lines and the normal (perpendicular) to S.
13. For a varying magnetic field, we first consider the magnetic flux through an
infinitesimal area element dS, where we may consider the field to be constant
:
From the definition of the magnetic vector potential A and the
fundamental theorem of the curl the magnetic flux may also be defined as:
where the line integral is taken over the boundary of the surface S, which is
denoted ∂S.
14. LAW
The most widespread version of Faraday's law states:
The induced electromotive force in any closed circuit is
equal to the negative of the time rate of change of the
magnetic flux through the circuit.
This version of Faraday's law strictly holds only when the closed circuit is
a loop of infinitely thin wire,and is invalid in other circumstances as
discussed below. A different version, the Maxwell–Faraday equation
(discussed below), is valid in all circumstances.
When the flux changes—because B changes, or because the wire loop is
moved or deformed, or both—Faraday's law of induction says that the wire
loop acquires an EMF , defined as the energy available per unit charge that
travels once around the wire loop (the unit of EMF is the volt).Equivalently, it
is the voltage that would be measured by cutting the wire to create an open
circuit, and attaching a voltmeter to the leads.
According to theLorentz force law (in SI units),
the EMF on a wire loop is:
15. where E is the electric field, B is the magnetic field (aka magnetic flux
density, magnetic induction), dℓ is an infinitesimal arc length along the wire,
and
the line integral is evaluated along the wire (along the curve the
conincident with the shape of the wire).
The Maxwell–Faraday equation states that a time-varying magnetic field is
always accompanied by a spatially-varying, non-conservative electric
field, and vice-versa. The Maxwell–Faraday equation is
where is the curl operator and again E(r, t) is the electric field and B(r, t)
is the magnetic field. These fields can generally be functions of position r
and time t.
The four Maxwell's equations (including the Maxwell–Faraday equation),
along with the Lorentz force law, are a sufficient foundation to
derive everything inclassical electromagnetism. Therefore it is possible to
"prove" Faraday's law starting with these equations. Faraday's law could be
taken as the starting point and used to "prove" the Maxwell–Faraday
equation and/or other laws.)
16. CONCLUSION
Faraday’sLawof Electromagnetic Induction, firstobserved and published
by MichaelFaradayinthe mid-nineteenthcentury, describesa very
important electro-magnetic concept. Althoughits mathematical
representationsare cryptic, the essence of Faraday’sisnot hard to grasp: it
relatesaninduced electric potentialor voltage to
a dynamic magnetic field. This concept has many far-reaching
ramifications that touch our lives in many ways: from the shining of the
sun, to the convenience of mobile communications, to electricity to
power our homes. We can all appreciate the profound impact
Faraday’s Law has on us.
BIBLIOGRAPHY
WIKIPEDIA
HOW STUFF WORKS