I don't think I have ever read about this but, what is it called when a secondary winding of a coil effects the primary winding like in a spark ignition coil? The secondaries flux must also cut the primarires,
Thank you for your expertise!

 

https://www.allaboutcircuits.com/te...chpt-9/mutual-inductance-and-basic-operation/

 

The secondaries flux must also cut the primarires,

Yes, the flux from the primary current and the secondary current combine together.
But because of the opposite direction of the two currents in the windings, the two fluxes actually subtract, and there is (ideally) a net zero change in the total flux.

 

The effect is magnetic induction, sometimes ELECTROMAGNETIC induction. AND it works both ways.