3. AIM:
To determine the faraday’s
law of electromagnetic
induction using a copper wire
wound over an iron rod and
a strong magnet
4. CERTIFICATE
This is to certify that the PHYSICS project titled
‘ELECTROMAGNETIC
INDUCTION’
has
been
successfully completed by C SAI SATHVICK of Class XII
in partial fulfillment of curriculum of CENTRAL BOARD
OF SECONDARYEDUCATION (CBSE) leading to the
award of annual examination of the year 2013-2014.
INTERNAL EXAMINER
TEACHER IN-CHARGE
5. ACKNOWLEDGEMENT
It gives me great pleasure to express my gratitude
towards our Physicsteacher MR P N SINGH for his
guidance, support and encouragement throughout
the duration of the project. Without her motivation
and help the successful completion of this project
would not have been possible.
C SAI SATHVICK
7. INTRODUCTION:
F
araday's law of induction 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
aspects of our daily life function because of the principles behind Faraday’s
Law. From natural phenomena such as the light we receive from the sun, to
8. 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.
9. 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.
10. 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
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.
11. 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.
12. 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:
13. 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.)
14. CONCLUSION
Faraday’s Law of Electromagnetic Induction, first observed and
published by Michael Faraday in the mid-nineteenth century,
describes a very important electro-magnetic concept. Although its
mathematical representations are cryptic, the essence of Faraday’s is
not hard to grasp: it relates an induced electric potential or 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
SCIENCE FOR ALL
