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Homework Help: Transformer current theory problem

  1. Apr 5, 2016 #1
    1. The problem statement, all variables and given/known data
    it is a long question so I have attached the question and picture

    2. Relevant equations
    I feel it is more theory based, which I explain below.
    3. The attempt at a solution
    I am unsure- but I would think it is from B to A for part B, as using the RHR, if the coils are wrapped this way and the flow is down through that column. But for part c) I am really unsure and I have tried reading multiple websites about solenoids, transformers and inductance but cannot find a clear answer. If b is B to A, then is the current in C in the opposite direction- opposing what is being produced by the primary, so it would be C to D in the diagram? Any help or clarification would be greatly appreciated. It was given as an extra problem though without a solution and it is really bothering me to not understand the concept behind it.

    Attached Files:

  2. jcsd
  3. Apr 6, 2016 #2

    Simon Bridge

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    Science Advisor
    Homework Helper

    It is not a long question - but the preamble is barely needed ... and AC current is provided to a transformer consisting of primary and secondary windings on an iron core. A diagram is provided showing the windings, and the direction magetic flux through the windings, at a specific instant.
    There are three questions, using the diagram
    (1) is this a step-up or step-down transformer
    (2) what is the direction of current through the primary
    (3) what is the direction of current through the secondary

    You are asking about (2) and (3).
    Sketching the overhead view so the magnetic flux through the primary goes into the page: the coil is wound top-to-bottom anticlockwise with B at the top and A at the bottom.
    If the current goes in at B, then it curls anticlockwise in this view ... hold your right hand in front of you and curl your fingers anticockwise: which direction does your thumb point? (Towards you or away from you?)
  4. Apr 6, 2016 #3
    Toward me? So from B to A?
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