EMF Induction in Solenoid

Thread Starter

QwertyXP

Joined Oct 18, 2013
4
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?
 

studiot

Joined Nov 9, 2007
4,998
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 ).
 

shortbus

Joined Sep 30, 2009
10,045
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),
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.
 

wayneh

Joined Sep 9, 2010
17,496
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.
 
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