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Let's take a transformer picture first.

The basic equation explaining how the transformer work is the equation of Faraday's law of induction.

[tex]\begin{array}{*{20}{c}}

{{V_P} = - {N_P}\frac{{d{{\rm{\Phi }}_B}}}{{dt}}\;\;\;\;\left( 1 \right).}\\

{{V_S} = - {N_S}\frac{{d{{\rm{\Phi }}_B}}}{{dt}}\;\;\;\;\left( 2 \right).}

\end{array}[/tex] A current in the primary winding

*I*generates B-field (magnetic field)

_{P1}*B*which induces a current in the secondary winding

_{1}*I*.

_{S1}*I*induces another B-field

_{S1}*B*which induces a new current in the primary

_{2}*I*.

_{P2}*I*also induces another B-field

_{P2}*B*which induces a new current in the secondary

_{3}*I*and so on.

_{S2}**So...I think that the magnetic flux**

*Φ*in above equations is a sum of all induced magnetic field*B*multiplied by a cross-section of the magnetic core. Could you tell me whether or not I'm right on this?_{1}+*B*_{2}+*B*_{3}...And

**when I think about Lenz's law, current directions in the attached picture is wrong.**The currents must be out of phase or opposite in directions in this picture. In order for currents to be in phase, one of the winding direction must be inverted. For example, in the primary winding, the winding should be done from back side to front side of the core (front side is the side facing reader) to achieve in-phase currents. Could you also confirm my opinion?

Thanks for reading my post and I'm waiting for any replies.