[SOLVED] Transformer core flux

In and ideal transformer all the flux is within the core. So if the flux is contained within the core how can it interact with the secondary winding. Does the flux not have to actually expand out through the layers of windings.

Current in the coil will generate flux through air or any medium, if you place a core, it is high permeabile so flux travel only in core.

Change in the current (AC) in the coil produce change in the magnetic flux in the core. As per Farady's law induced emf generated in the secondary due to mutual inductance

Hi,

It does expand out from the winding and later collapse into the winding. That's how it gets to induce emf on the other windings. However, the core has less reluctance as compared to air (or free space) so the flux quickly prefers to stay confined within the core and not go (expand) any farther.

If you apply DC to the terminals of one winding, a flux will build up and expand through the other windings. Each of the other windings get induced with emf in one direction depending on the direction of the current. This flux will then stay confined to the core as long as the DC voltage remains connected to those terminals. When you disconnect the source, the flux will collapse out of the core through the windings and back into the winding that generated it. At that point, the other windings gets induced with emf again, but this time in the opposite direction.

- - - Updated - - -

smijesh said:

Current in the coil will generate flux through air or any medium, if you place a core, it is high permeabile so flux travel only in core.

Change in the current (AC) in the coil produce change in the magnetic flux in the core. As per Farady's law induced emf generated in the secondary due to mutual inductance

Click to expand...

What is meant by mutual inductance then if the flux doesn't cut through the other winding?

It does pass through the air and cut through the other winding but it takes a negligible period of time to do that compared to the time it stays confined in the core.

The direction of travel you are referring to is just the north-pole-to-south-pole direction.

So if the flux is contained within the core how can it interact with the secondary winding.

Click to expand...

Even more, how can it be generated by the primary winding? It's a very basic property of magnetic induction, which can be described by a line integral. Review your physics text books.

Akanimo said:

Hi,

What is meant by mutual inductance .

Click to expand...

Between the two coils is defined as the property of the coil due to which it opposes the change of current in the other coil, or you can say in the neighboring coil. When the current in the neighboring coil is changing, the flux sets up in the coil and because of this changing flux emf is induced in the coil called Mutually Induced emf and the phenomenon is known as Mutual Inductance