PRODUCTION OF INDUCED EMF

7/30/2019 PRODUCTION OF INDUCED EMF

1/28


2/28

1

INDEX:Certificate_______________2Acknowledgement___________3Aim ______________________5Introduction______________6Theory___________________11Apparatus________________15Construction_____________16Working__________________17Observation______________23Observation Table________24Result___________________25Bibliography_____________26


3/28

2

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


4/28

3

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


5/28

4

PRODUCTIONOF INDUCED

EMF


6/28

5

AIM

TODEMONSTRATETHEPRODUCTIONOF

INDUCEDEMFI NACOILDUETOTHE

OSCILLATORYPENDULUMMOVEMENT

OFBARMAGNETSTOWARDSANDAWAY

FROMI TANDTOSTUDYTHECURRENT

VARIATIONBYVARYINGTHECOIL WINDINGANDTHESIZEOFMAGNETI N

THEGIVENMODEL.


7/28

6

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


8/28

7

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.


9/28

8

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).


10/28

9

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


11/28

10

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


12/28

11

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.


13/28

12

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.


14/28

13

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


15/28

14

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.


16/28

15

COMPONENTUSED

Coil ....................... (28 SWG wire)

Magnet ................. (Bar Magnet 2 inch)

Meter .................... (250 Ampere

rating)

Misc. ..................... Wires, spares etc.


17/28

16

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.


18/28

17

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.


19/28

18

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.


20/28

19

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.


21/28

20

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.


22/28

21

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


23/28

22

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.


24/28

23

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.


25/28

24

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.


26/28

25

Observation Table

S.no. No of turns

(N)

Produced E.M.F

(VOLTS)

1 1000 1

2 2000 1.53 3000 2


27/28

26

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.


28/28

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

PRODUCTION OF INDUCED EMF

Documents

Transcript of PRODUCTION OF INDUCED EMF