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Induced current

  1. Jul 9, 2015 #1
    why is current produced in a coil if it is placed near other current caarrying coil
  2. jcsd
  3. Jul 9, 2015 #2
    If a current is run through a coil, it will produce an electromagnetic field around the coil. If a different coil is placed inside that field, the electromagnetic field from the first will induce a current in the second.
  4. Jul 9, 2015 #3


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    with the important point that the current in the first coil must be alternating ( oscillating)

    ie. if it is a non varying DC current, there will be no induced voltage/current into the second coil
  5. Jul 10, 2015 #4
    He hasn't asked question clearly but he was mean that what happen if two coil both are supplied power placed near?
  6. Jul 10, 2015 #5
    Hello Alph and welcome.. sorry but your comment was not clear at all.
  7. Jul 10, 2015 #6


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    that just doesn't make sense at all
  8. Jul 11, 2015 #7
    but how actually is the current produced
  9. Jul 12, 2015 #8


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  10. Jul 12, 2015 #9


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  11. Jul 14, 2015 #10
    See: Maxwell Equations. They'll give you the answer you want much more eloquently and clearly than I can.
  12. Jul 14, 2015 #11
    One of the benefits of this topic is that it can be broken down into smaller parts:

    1) Current flow produces a magnetic field - even when you pass DC current though a conductor, or a wrapped coil of conductors, at the initial "turn on" the magnetic field is changing, once the DC current has reached steady state - the magnetic field is no longer changing - but is still there!

    2) A changing magnetic field will induce a current in a conductor that intersects the conductor. This is induction -- if we move a conductor through a static (non-changing ) field we induce current. (permanent magnet generator with stationary magnets and moving windings) - if we hold a conductor stationary and move the magnet (field), current is also induced.

    Commonly described as when magnetic flux lines* cut through a conductor current is induced. ( the purists here will be offended by the notion of magnetic flux lines - however that is the common introduction - they are not truly lines - the Mag Field is continuous, personally I suppose this notion comes from studying magnetic with iron filings - when you do this you see lines - but I digress... )

    So in general we look at (study) creating magnetic fields - with magnets or with electromagnets-- once the field is established it does not matter HOW it is created.

    OK - now take a conductor or coil (coil A), and turn the current on and off... you can understand you are creating and stopping a magnetic field. If you reverse the current the magnetic field is also reversed.

    Now put another conductor or coil (coil B) - in the area of Coil A above (physical alignment of the conductors or coils does matter )... as the magnetic flux from coil A is not expanding and collapsing -- it is intersecting whit the Conductors in Coil B, this magnetic field induces current in Coil B.
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