Determining direction of induced current

  1. How do you determine that direction of the AC current at a given instant in this model. Does it really matter? The red arrows change direction when the coil is horizontal. Does anyone know why the current changes direction at that point? Why does it switch direction at the horizontal and not the vertical?

    Last edited: Dec 9, 2011
  2. jcsd
  3. The link doesn't work.
  4. PeterO

    PeterO 2,319
    Homework Helper

    Link doesn't work. is the magnetic field vertical or horizontal?
  5. Link doesn't work.
    The direction of induced current is determined by Flemming's Right Hand rule. Read about it and you will answer your questions yourself, unless you provide a working link.
  6. Sorry about the link. I fixed it if anyone can still take a look at a and explain why the current switches when the coils are parallel and not vertical with the ground that would be of much help. I tried looking up this information online but I can't seem to find an answer that directly answers this question. So if anyone has any information that is good at explaining what determines that direction of AC current at a given position in respect to a magnet this would be much appreciated. Again sorry for the bad link.
  7. You must first understand the Flemming's Right Hand Rule. It concludes that magnetic field, direction of induced current and the force acting on the current carrying conductor are all mutually perpendicular. The armature(or the coil) is therefore positioned parallel to ground such that it is perpendicular to the direction of magnetic field which is shown by blue arrow lines.
    Again, as I said, read Flemming's Rules
  8. PeterO

    PeterO 2,319
    Homework Helper

    The direction of the induced current will change at the point where the loop is perpendicular to the field.
    Since the magnetic field is vertical, the loop is horizontal as the change takes place.

    Many examples of generators pictured, have the field horizontal - perhaps you failed to notice the difference.
  9. Thank for the Help! Is if fair to say that technically there is always a small current (very small) since technically the coil is not at any point perpendicular to the field because it is 3 dimensional so a small voltage could be produced in the small part of the coil that is perpendicular to the field?
  10. PeterO

    PeterO 2,319
    Homework Helper

    I think it is more logical to say that if the current is at one time in one direction, and a short time later in the reverse direction, then at some time between, there must have been no current - even if only for a single instant.

    Otherwise it is like saying you can be driving forward, select reverse and back up without ever stopping??
  11. There can't be an instant when no current is induced. Because the current induced is maximum at 90 angle with magnetic field and at subsequent angles, it reduces. But look at the function of rings in detail.
  12. PeterO

    PeterO 2,319
    Homework Helper

    Please try graphing the current as a function of time, showing positive and negative values, but without crossing the axis -where the current is zero ?
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