Drie-dimensionale magneetvelden en toch simpele vervangingsschema's

IN COILS AND IN TRANSFORMERS COMPLICATED THREEDIMENSIONAL MAGNETIC FIELDS ARE PRESENT. NORMALLY WE TRY TO CHARACTERIZE THE INDUCTION EFFECTS OF THESE FIELDS IN SIMPLE SCALAR QUANTITIES, SELF-INDUCTANCES (L) AND MUTUAL INDUCTANCES (M), WHICH ARE THEN USED IN THE MUCH SIMPLER EQUIVALENT CIRCUIT. IT IS IMPORTANT TO REALIZE HOW BIG THE STEP IS FROM THREEDIMENSIONAL FIELD TO SCALAR L’s AND M’s. Two EXAMPLES ARE DISCUSSED: TWO COUPLED RINGS WITHOUT IRON AND A TRANSFORMER WITH IRON.