设两个半环式的螺线管的自感系数为L', L=2L'+2M dl d L<L/2 8=-(L dl dt dt =-(L'+M d d +M al dt dt =-(L'+M d 6=6,+82=-(2L'+2M) 比较: 8=-1 dt 9 9 设两个半环式的螺线管的自感系数为L’ , I I d t d I L M d t d I M d t d I (L ) ( ) 1 = − + = − + d t d I L M d t d I M d t d I (L ) ( ) 2 = − + = − + dt d I (2L 2M ) = 1 + 2 = − + 比较: dt dI = −L L = 2L + 2M L’< L / 2