穿过外管的全磁通: V12=N B2 ds 2R,2R2 N1B2内S2 N,mMmm 2·zR2 12 又:L1=m1=(1)2·zR2=mR2 R ∵.M R2穿过外管的全磁通： = =  =   1 2 2 12 1 2 d 1 N B S N B S s 内    2 2 2 1 2 I R l N N   N1 N2 l 2R1 2R2 L1 L2 2 I 2 12 I M  = 2 2 1 2 R l N N =   又： 2 1 1 2 1 2 1 1 ( ) l R l N L = n V =   2 1 2 1 R l N =   2 2 2 2 2 R l N L =   1 2 1 2 L L R R M =