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Electricity and Magnetism
 Aim: to verify the Faraday/Neumann Law of Electro-Magnetic-Induction See The Laws of Electro-Magnetic Induction The method suggested here uses this basic circuit An alternating current, I of variable frequency, flowing in one coil (the primary coil), induces an alternating emf, E, in the other coil (the secondary coil). Set the signal generator to give a triangular signal so that the rate of change of current is of constant magnitude (for a given frequency). Method To see what is happening, it is recommended to use a dual beam oscilloscope (or computer with software to simulate one). We include in the primary circuit a resistance (of a few hundred ohms). The voltage across this resistance varies in the same way as the current flowing through it so one beam of the oscilloscope can be used to show how the current I is varying. Your apparatus might look different from the diagram below but the basic connections will be similar. After a bit of messing about with the oscilloscope controls, you should be able to have obtain something like this: Note that this image confirms that the induced emf is constant when the rate of change of current (and therefore the rate of change of magnetic flux) is constant. By varying the frequency of the supply and measuring the induced emf it is now possible to verify the law. It is recommended that you keep the image of the voltage across R visible so that you can keep it at constant amplitude throughout the experiment (this makes the analysis of the results easier). In practice it is convenient to use two coils wound on the same support, in order to have a better flux linkage between the two coils. Unfortunately one often finds that two coils are actually two halves of one long coil. If this is the case, it is still possible to use the same method but you must make sure that you use a signal generator that has a "floating" output (that is, one which does not have one side of the output connected to earth). The simplest way to do this is to use a battery powered signal generator.

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