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INDEX:Certificate_______________2Acknowledgement___________3Aim ______________________5Introduction______________6Theory___________________11Apparatus________________15Construction_____________16Working__________________17Observation______________23Observation Table________24Result___________________25Bibliography_____________26
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CERTIFICATEThis is to certify that the PHYSICS project titledELECTROMAGNETIC INDUCTION has been
successfully completed by PUSHKAR MITTAL ofClass XII A in partial fulfillment of curriculum ofCENTRAL BOARD OF SECONDARY EDUCATION(CBSE) leading to the award of annual examination ofthe year 2012-2013.
INTERNAL EXAMINER TEACHER IN-CHARGE
SCHOOL SEAL PRINCIPAL
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ACKNOWLEDGEMENTFirst and foremost I would like to thank my
Teacher Mr.PRAVEEN KAPOORwho has
assigned me this term paper to bring out
My creative capabilities.
I express my gratitude to my parents for being a
continuous source of encouragement for all theirfinancial aid.
I would like to acknowledge the assistance provided to
me by the library staff ofBAL BHARATI PUBLIC
SCHOOL.
My heartfelt gratitude to my classmates and for helpingme to complete my work in time.
- Pushkar Mittal
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PRODUCTIONOF INDUCED
EMF
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AIM
TODEMONSTRATETHEPRODUCTIONOF
INDUCEDEMFI NACOILDUETOTHE
OSCILLATORYPENDULUMMOVEMENT
OFBARMAGNETSTOWARDSANDAWAY
FROMI TANDTOSTUDYTHECURRENT
VARIATIONBYVARYINGTHECOIL WINDINGANDTHESIZEOFMAGNETI N
THEGIVENMODEL.
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INTRODUCTION:araday's law of induction is a basic lawofelectromagnetismthat predicts how a magnetic
fieldwill interact with anelectric circuitto produce
anelectromotive force (EMF). It is the
fundamental operating principle oftransformers,inductors,
and many types ofelectricalmotorsandgenerators.
Electromagnetic inductionwas discovered independently
byMichael FaradayandJoseph Henryin 1831; however,
Faraday was the first to publish the results of his
experiments. Faraday explained electromagnetic induction
using a concept he calledlines of force. These equations for
electromagnetics are extremely important since they provide
F
http://en.wikipedia.org/wiki/Electromagnetismhttp://en.wikipedia.org/wiki/Electromagnetismhttp://en.wikipedia.org/wiki/Electromagnetismhttp://en.wikipedia.org/wiki/Magnetic_fieldhttp://en.wikipedia.org/wiki/Magnetic_fieldhttp://en.wikipedia.org/wiki/Magnetic_fieldhttp://en.wikipedia.org/wiki/Electric_circuithttp://en.wikipedia.org/wiki/Electric_circuithttp://en.wikipedia.org/wiki/Electric_circuithttp://en.wikipedia.org/wiki/Electromotive_forcehttp://en.wikipedia.org/wiki/Electromotive_forcehttp://en.wikipedia.org/wiki/Electromotive_forcehttp://en.wikipedia.org/wiki/Transformerhttp://en.wikipedia.org/wiki/Transformerhttp://en.wikipedia.org/wiki/Transformerhttp://en.wikipedia.org/wiki/Inductorhttp://en.wikipedia.org/wiki/Inductorhttp://en.wikipedia.org/wiki/Inductorhttp://en.wikipedia.org/wiki/Electricityhttp://en.wikipedia.org/wiki/Electricityhttp://en.wikipedia.org/wiki/Electric_motorhttp://en.wikipedia.org/wiki/Electric_motorhttp://en.wikipedia.org/wiki/Electric_motorhttp://en.wikipedia.org/wiki/Electrical_generatorhttp://en.wikipedia.org/wiki/Electrical_generatorhttp://en.wikipedia.org/wiki/Electromagnetic_inductionhttp://en.wikipedia.org/wiki/Electromagnetic_inductionhttp://en.wikipedia.org/wiki/Michael_Faradayhttp://en.wikipedia.org/wiki/Michael_Faradayhttp://en.wikipedia.org/wiki/Michael_Faradayhttp://en.wikipedia.org/wiki/Joseph_Henryhttp://en.wikipedia.org/wiki/Joseph_Henryhttp://en.wikipedia.org/wiki/Joseph_Henryhttp://en.wikipedia.org/wiki/Lines_of_forcehttp://en.wikipedia.org/wiki/Lines_of_forcehttp://en.wikipedia.org/wiki/Lines_of_forcehttp://en.wikipedia.org/wiki/Lines_of_forcehttp://en.wikipedia.org/wiki/Joseph_Henryhttp://en.wikipedia.org/wiki/Michael_Faradayhttp://en.wikipedia.org/wiki/Electromagnetic_inductionhttp://en.wikipedia.org/wiki/Electrical_generatorhttp://en.wikipedia.org/wiki/Electric_motorhttp://en.wikipedia.org/wiki/Electricityhttp://en.wikipedia.org/wiki/Inductorhttp://en.wikipedia.org/wiki/Transformerhttp://en.wikipedia.org/wiki/Electromotive_forcehttp://en.wikipedia.org/wiki/Electric_circuithttp://en.wikipedia.org/wiki/Magnetic_fieldhttp://en.wikipedia.org/wiki/Magnetic_fieldhttp://en.wikipedia.org/wiki/Electromagnetism -
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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 Faradays Law of
Electromagnetic Induction can be beneficial since so many
aspects of our daily life function because of the principles
behind Faradays Law. From natural phenomena such as the
light we receive from the sun, to technologies that improve
our quality of life such as electric power generation,
Faradays Law has a great impact on many aspects of our
lives.
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Faradays 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
Faradays Law comes from the work of Heinrich Lenz, a
Russian physicist who made his contribution to Faradays
Law, now known as Lenzs Law, in 1834 (Institute of
Chemistry).
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Faradays 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.
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 moderntoroidal transformer) to
induce current
Figure 1 Faraday's First Experiment
http://en.wikipedia.org/wiki/Torushttp://en.wikipedia.org/wiki/Toroidal_transformerhttp://en.wikipedia.org/wiki/Toroidal_transformerhttp://en.wikipedia.org/wiki/Toroidal_transformerhttp://en.wikipedia.org/wiki/Torus -
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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 (seeLorentz force), and the transformer
EMF generated by an electric force due to a changing
magnetic field (due to theMaxwellFaraday
equation).James Clerk Maxwelldrew attention to this fact in
his 1861 paperOn 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.
http://en.wikipedia.org/wiki/Lorentz_force#Force_on_a_current-carrying_wirehttp://en.wikipedia.org/wiki/Lorentz_force#Force_on_a_current-carrying_wirehttp://en.wikipedia.org/wiki/Lorentz_force#Force_on_a_current-carrying_wirehttp://en.wikipedia.org/wiki/Faraday's_law_of_induction#Maxwell.E2.80.93Faraday_equationhttp://en.wikipedia.org/wiki/Faraday's_law_of_induction#Maxwell.E2.80.93Faraday_equationhttp://en.wikipedia.org/wiki/Faraday's_law_of_induction#Maxwell.E2.80.93Faraday_equationhttp://en.wikipedia.org/wiki/Faraday's_law_of_induction#Maxwell.E2.80.93Faraday_equationhttp://en.wikipedia.org/wiki/Faraday's_law_of_induction#Maxwell.E2.80.93Faraday_equationhttp://en.wikipedia.org/wiki/Faraday's_law_of_induction#Maxwell.E2.80.93Faraday_equationhttp://en.wikipedia.org/wiki/James_Clerk_Maxwellhttp://en.wikipedia.org/wiki/James_Clerk_Maxwellhttp://en.wikipedia.org/wiki/James_Clerk_Maxwellhttp://en.wikipedia.org/wiki/File:On_Physical_Lines_of_Force.pdfhttp://en.wikipedia.org/wiki/File:On_Physical_Lines_of_Force.pdfhttp://en.wikipedia.org/wiki/File:On_Physical_Lines_of_Force.pdfhttp://en.wikipedia.org/wiki/James_Clerk_Maxwellhttp://en.wikipedia.org/wiki/Faraday's_law_of_induction#Maxwell.E2.80.93Faraday_equationhttp://en.wikipedia.org/wiki/Faraday's_law_of_induction#Maxwell.E2.80.93Faraday_equationhttp://en.wikipedia.org/wiki/Lorentz_force#Force_on_a_current-carrying_wire -
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THEORY:Magnetic flux
Very qualitatively, f luxis a measure of how much of a vectorfield passes perpendicularly through a given area. A vector field is
simply a vector quantity that has possibly different values (in
magnitude and/or direction) at different points in space. Examples
of vector fields are thevelocity of air molecules in a room or of
water molecules in a stream, the acceleration due to gravity at
various locations on and above the earths surface, the electric
field surrounding a charged balloon, or the magnetic field in the
region around a solenoid with current flowing through itswindings. (This explains why the latter two examples are
called fields; we can also speak of the gravitational field around
the earth, which is equivalent to the third example listed.) In all of
these cases, the vector quantity being described varies withposition in space.
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In this lecture we will be talking about the flux of
the magnetic field. However, it will be important to keep in mind
that we can speak just as well of the flux of air molecule velocities
or the flux of the electric field as we can of the flux of the magnetic
field. (See the homework at the end of this lecture for specificexamples.)
Again, magnetic fluxis a measure of how much magnetic field
passes perpendicularly through a given area. Consider the flatloop of area A formed by N turns of wire shown in Fig. 18.2.
A uniform magnetic fieldBpasses perpendicularly through theturns of wire forming the loop. The net f lux of the magnetic
fi eld B, denotedFB(F is the capital Greek letter phi), through the
area A in this case is given by
We see that, if we increase the area A or the magnetic field
magnitude B or the number of turnsN, we will increase the net
magnetic flux FB. All of these should make perfect sense in light ofour qualitative understanding of flux. (The net flux is the total flux
through all of the loops of wire, if there are more than one.)
Consider now the situation shown in Fig. 18.3.
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Again, we have N turns of wire defining the area A, and again the
magnetic field is uniform. But this time the magnetic field does not
point perpendicular to the area A, but rather makes an angleq with
the perpendicular direction to the loop (the normal direction to the
plane of the loopdo you remember the normal force and what
direction it pointed?) Figure 18.4 shows the same set-up as in Fig.
18.3, but now shows just one magnetic field vector (so that we can
concentrate on just it and not worry about all of the others
cluttering things up). Any vector can be broken down into two
perpendicular components (like x and y components). We show in
Fig. 18.4 the magnetic field vector broken down intocomponents perpendicular and parallel to the plane of the loop.
From our qualitative understanding of flux, we know that only
the perpendicular part of the field will contribute
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to FB. (The parallel component just runs along the surface, and
does not passthrough it at all.) From a straight-forward extension
of Eq. (18.1), we get that, in this case, the net magnetic fluxthrough the loop is given by
This is the mathematical definition of magnetic flux that we will be
using in this course. (This definition assumes that the component
of magnetic field passing perpendicular to the area isconstant over
the whole area, and that the area is flat. If this is not the case,
then calculus would have to be used to find the flux. We wont
worry about that here!) Note that in the set-up of Fig. 18.4, Eq.
(18.2) becomes
For any given set-up, you must first find the component of the
magnetic field perpendicular to the area under consideration, and
then multiply that component by the area and the number of turnsin order to find the flux through the loop.
The unitsof magnetic flux must be the units of number of turns (nounits), times the units ofmagnetic field (T) times the units
of area (m2).
Units of magnetic flux: T m2
.
This combination of units is sometimes called a weber (Wb), butwe wont use this unit in this course.
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COMPONENTUSED
Coil ....................... (28 SWG wire)
Magnet ................. (Bar Magnet 2 inch)
Meter .................... (250 Ampere
rating)
Misc. ..................... Wires, spares etc.
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CONSTRUCTION
Take about few meters of No. 28 insulated bell wire. Windit around the end of a plastic bobbins (app. 5000 turns),
making a close, even coil. Connect this bobbin to any wood
base with a slight bend. Tie the ends of the coil to the
terminals of your galvanometer (Figure) since the coil
should be kept at least 6 Inch away from the galvanometer,
you must use wire leads at least 6 Inch in length. Otherwise
the magnet will affect the needle. The coil is close to thegalvanometer in Figure so as the apparatus shown in the
illustration.
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WORKING
What to Do
Take a permanent bar magnet in one hand
and swiftly thrust one pole of the magnetthrough the coil of wire and leave the
magnet in the coil. Watch the needle of the
galvanometer. It kicks sharply to one side.
This proves that an electric current flows
through the coil.
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But notice also that the needle swings back
to center and stops when the magnet stops
moving.Quickly pull the magnet out of the coil.
The needle again kicks sharply, but in the
opposite direction. It again swings back to
center and stops when the magnet stops
moving. This shows that the current flows
only while the magnet is in motion.
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To Take Observation
Push the bar into the coil and pull in outseveral times in succession with different
coils. The pushing and pulling motion of
the magnet keeps the needle swinging
from one side to the other as long as you
keep up the push-pull movement.
Generation of Alternating Current
You are generating an alternatingcurrent in the coil. The alternating
current flows in one direction when you
push the bar in, but the current reverses
and flows in the opposite direction when
you pull the bar out. The needle does notswing over the one side and stay there as
it did when you sent direct current from
a dry cell through a coil.
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Hold the magnet still and move the coil
back and forth along the magnet. Theneedle swings back and forth as it did
when you held the coil still and moved
the magnet in and out of the coil. You
can readily see that, whether you hold
the coil still and move the magnet orhold the magnet still and move the coil.
Alternating current is produced.
Turn the magnet around and move the
other end in and out of the coil. Does thegalvanometer needle behave differently?
How? Explain.
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You have just completed a modern
version of Faradays historic
experiment. You have generated a crude
kind of alternating-current electricitywith a crude electromagnetic generator,
just as he did. You used a magnet, a coil,
and motion (MCM). But you may wonder
how a magnet in motion can generate
electricity. Although we are accustomedto say that we generate electricity, we
cannot generate electricity with our
apparatus any more than we can
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generate water by working a pump. Both
water and electricity already exist. The
water is inside the pipes. The electricity,in the form of electrons, is in the wires of
the coil and in the rest of the circuit. In
neither case do we generate or create.
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OBSERVATIONS When a bar magnet is placed near the coil no
deflection is observed in galvanometer.
When North Pole of magnet is moved rapidly towardsthe coil, the galvanometer shows deflection. When
magnet is stopped the deflection in galvanometer
becomes zero. When speed of magnet is increased the
deflection is increased.
When North Pole of magnet is taken away from thecoil rapidly, the galvanometer shows deflection but in
opposite direction. When magnet is stopped the
deflection in galvanometer becomes zero. When speed
of magnet is increased the deflection is increased.
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When South Pole of magnet faces the coil & themagnet is moved towards or away from the coil, the
galvanometer again shows deflection but in oppositedirection.
When magnet is kept stationary & coil is movedtowards or away from magnet, then there is a
deflection in the galvanometer.
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Observation Table
S.no. No of turns
(N)
Produced E.M.F
(VOLTS)
1 1000 1
2 2000 1.53 3000 2
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RESULTWhen there is no relative motion between the
magnet& the coil, the magnetic lines of forcepassing through the coil is definite i.e. themagnetic flux linked with coil is constant.
When there is relative motion between themagnet &coil & magnet is moved towards the coilthe magnetic lines passing through coil increases.
When magnet moves away, magnetic field linespassing through coil decreases.
According to Faraday Laws. E.M.F. induced whenmagnetic flux linked with coil can be changed.
When magnetic flux linked with coil increasesthen galvanometer shows deflection inone direction but when it decreases it showsdeflection in opposite direction.
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BIBLIOGRAPHYWIKIPEDIA
HOW STUFF WORKS
SCIENCE FOR ALL
Discovery Channel
How its made
How Stuff works
Google
AND AT LAST NEVER ENDING EFFORTS OF
OUR PHYSICS TEACHER
Mr. Praveen Kapoor