lab35 - LAB# 35: MAGNETIC FIELD OF A...

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LAB# 35: MAGNETIC FIELD OF A CURRENT-ELECTROMAGNETIC INDUCTION INTRODUCTION: In 1820 Hans Christian Oersted discovered during the course of a physics demonstration for his students that there is a magnetic field associated with an electric current. The reverse effect, that an electric current might be caused by a magnetic field was developed in 1831 by Faraday in England and Henry in the United States. Their experiments can be summed up as: an emf, (electro-motive force) is induced in a conductor whenever there is a change in the magnetic flux linked with the conductor. This change of flux can be produced in several ways for example moving one conductor near a current-carrying conductor. The generation of an emf by this process is called electromagnetic induction. If the emf is induced in a conductor that is part of a closed circuit, there will be an electric current induced in that circuit. The emf induced in a circuit is found to depend only upon the number of turns N in the circuit, the change in the magnetic flux Δφ , and the time Δτ required to produce this change. The average induced emf ε is given by: ! = " N # $ # % (1) The induced current developed by electro-magnetic induction is in such a direction as to oppose (by its magnetic action) the change inducing the current. This is why a negative sign is introduced into equation 1 (above). This equation is the principle of Lenz’s Law and is a good example of the conservation of energy. An induced current can produce heat or do either chemical or mechanical work. The energy must come from the work
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This note was uploaded on 02/29/2012 for the course PHYS 227 taught by Professor Rabe during the Fall '08 term at Rutgers.

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lab35 - LAB# 35: MAGNETIC FIELD OF A...

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