ELECTROMAGNETICINDUCTION
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
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 2016-2017.
INTERNAL EXAMINER TEACHER IN-CHARGE
ACKNOWLEDGEMENT
It gives me great pleasure to express my gratitude towards our Physicsteacher MR ......
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.
…………………
APPARATUS
1. Insulated copper wire
2. A iron rod
3. A strong magnet and
4. A light emitting diode (LED)
INTRODUCTION:
F
araday's law of inductionis a basic law ofelectromagnetismthat predicts how amagnetic 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 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 moderntoroidal 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: themotional EMFgenerated by a magnetic force on a moving wire (seeLorentz force), and thetransformerEMFgenerated by an electric force due to a changing magnetic field (due to the Maxwell–Faraday 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.
THEORY:
Magnetic flux:
Themagnetic flux(often denoted Φ or ΦB) through a surface is the component of theBfieldpassing through that surface. TheSIunitof magnetic flux is theweber(Wb) (in derived units: volt-seconds), and theCGSunit is themaxwell. 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 ofvector areaSis
whereBis the magnitude of the magnetic field (the magnetic flux density) having the unit of Wb/m2(Tesla),Sis the area of the surface, andθis the angle between the magneticfield linesand thenormal (perpendicular)toS.
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 themagnetic vector potentialAand thefundamental theorem of the curlthe magnetic flux may also be defined as:
where theline integralis taken over the boundary of the surfaceS, 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 themagnetic fluxthrough 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 discussedbelow. A different version, theMaxwell–Faraday equation(discussedbelow), is valid in all circumstances.
When the flux changes—becauseBchanges, or because the wire loop is moved or deformed, or both—Faraday's law of induction says that the wire loop acquires anEMF, defined as the energy available per unit charge that travels once around the wire loop (the unit of EMF is thevolt).Equivalently, it is the voltage that would be measured by cutting the wire to create anopen circuit, and attaching avoltmeterto the leads.
According to theLorentz force law(inSI units),
the EMF on a wire loop is:
whereEis theelectric field,Bis themagnetic field(aka magnetic flux density, magnetic induction), dℓis an infinitesimalarc lengthalong the wire, and theline integralis 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-conservativeelectric field, and vice-versa. The Maxwell–Faraday equation is
whereis thecurloperatorand againE(r,t) is theelectric fieldandB(r,t) is themagnetic field. These fields can generally be functions of positionrand timet.
The fourMaxwell's equations(including the Maxwell–Faraday equation), along with theLorentz force law, are a sufficient foundation to deriveeverythinginclassical 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