ELECTROMAGNETIC INDUCTION

BY

KARTHIK PREMANAND

XII ROSE

ROLL NO:17

INDEX:

Aim

Certificate

Acknowledgement

Apparatus

Introduction

Theory

Conclusion

Bibliography

AIM:

To determine the faraday’s

law of electromagnetic

induction using a copper wire

wound over an iron rod and

a strong magnet

CERTIFICAT

E

This is to certify that the PHYSICS project titled

‘ELECTROMAGNETIC INDUCTION’ has been

successfully completed by KARTHIK PREMANAND of

Class XII ROSE in partial fulfillment of curriculum of

CENTRAL BOARD OF SECONDARY EDUCATION

(CBSE) leading to the award of annual examination of the

year 2012-2013.

INTERNAL EXAMINER TEACHER IN-CHARGE

SCHOOL SEAL PRINCIPAL

ACKNOWLEDGEMENT

First and foremost I thank my teacher Mrs.

VEMURI who 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 their financial aid.

I would like to acknowledge the assistance provided to me by

the library staff of BAL BHARATI PUBLIC SCHOOL.

My heartfelt gratitude to my classmates and for helping me to

complete my work in time.

Karthik Premanand

APPARATUS

1. Insulated copper

wire 2. A iron rod 3. A strong magnet

and 4. A light emitting

diode (LED)

INTRODUCTION:

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.

F

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 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.

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 transformer EMF 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.

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.

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.

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 the Lorentz force law (in SI units),

the EMF on a wire loop is:

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.)

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

EXPERIMENT PHOTOs