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I read this online, " For a travelling magnetic field in a circle, the induced magnetic field in the armature of the generator will be sinusoidal. That's why the generated voltage is a sinusoid, exactly at the same frequency as the generator is turning." I understand that the angular motion is responsible for the sine wave, however, I am very confused about what induces which. I thought magnetic field was either created with a permenant magnet or flow of charge, and that what magnetic field induces was emf, not another magnetic field. Sorry, if these all sound stupid, it all gets confusing after some time, and I don't know where to start.

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  • \$\begingroup\$ Notice they specified the magnetic field is travelling in a circle. Without a diagram I am not sure exactly what it means for the field to be "travelling", but I expect the circular form is critical here. \$\endgroup\$ – The Photon Dec 28 '18 at 19:43
  • \$\begingroup\$ Magnetic fields aren’t induced so either you’ve misquoted the source or the source is unreliable. Voltages or emfs are induced by a changing magnetic field as per Faraday’s law of induction. \$\endgroup\$ – Andy aka Dec 28 '18 at 19:43
  • \$\begingroup\$ Can it be a magnet rotating on its own axis? I have no idea. I was searching about how we get sine wave of voltage with a generator, all got confusing, every source explains it differently, especially this one. \$\endgroup\$ – Vyun Dec 28 '18 at 20:32
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A synchronous generator has a rotating magnetic field that is produced by a permanent magnet or a wound field (electromagnet). The direction of the magnetic field is such that the stator conductors pass through the flux of each pole as the rotor turns. It is the reversal of flux from one pole to the next that induces AC voltage.

For the induced voltage to be sinusoidal, the shape of the magnetic field must be sinusoidal. Designing winding configuration and the poles of the rotor to produce sinusoidal voltage is a complex task that is described in detail in electric machinery text books.

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  • \$\begingroup\$ Thank you! What is the relation between the induced voltage and magnetic field (their direction, magnitude and such), so that the induced voltage has the same wave shape as the magnetic field? \$\endgroup\$ – Vyun Dec 28 '18 at 23:32
  • \$\begingroup\$ You need a text book or the equivalent presentation in an online format. First learn the basics with simple diagrams. Then look at a real generator design. \$\endgroup\$ – Charles Cowie Dec 29 '18 at 0:44
  • \$\begingroup\$ I try to learn intuitively, how's that going to help me I don't know. I have engineering textbooks at home including Chapman, not helpful at all. Thank you anyway. \$\endgroup\$ – Vyun Dec 29 '18 at 18:32
  • \$\begingroup\$ It would be nice to have intuitive explanations for everything, but the theory and math are also important. I have several paper texts and several electronic texts, but I am not sure that I could piece together a satisfactory intuitive explanation. It would be like trying to write a good portion of a text chapter using existing texts and improving on them. \$\endgroup\$ – Charles Cowie Dec 29 '18 at 19:39

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