EMF Induction in Solenoid

Discussion in 'General Electronics Chat' started by QwertyXP, Oct 18, 2013.

  1. QwertyXP

    Thread Starter New Member

    Oct 18, 2013
    Assuming that both the windings of a transformer is wrapped around an iron core, how is an EMF induced in the secondary winding - isn't it necessary for flux to cut through the winding in order to induce an EMF?

    Most of the flux from the primary remains inside the iron core while completing its loop and very little of it cuts the secondary winding (in an ideal transformer all the flux should remain inside the core), so very little power should be transferred to the secondary winding - but in a transformer nearly all the power from the primary is transferred... What am I missing here?
  2. studiot

    AAC Fanatic!

    Nov 9, 2007
    Nothing is cut.

    The EMF is induced in any closed loop formed by a conductor that the magnetic flux "threads". That includes both the seconday and the primary windings.
    Threads means that the lines of flux pass through the plane of the loop.

    The induction occurs because the strength of the flux changes and is proportional to the rate of change of flux (Lenz & Faraday's laws ).
    QwertyXP likes this.
  3. shortbus

    AAC Fanatic!

    Sep 30, 2009
    If this, "in an ideal transformer all the flux should remain inside the core", was true, a transformer, mechanical solenoid, or electric motor would not work. The "core" intensifies the magnetic force made by electricity, not contain it.
  4. wayneh


    Sep 9, 2010
    The best transformer core loses no flux. Think of a toroid. Motors and solenoids are different beasts that require breaks and the attendant flux losses.