4.6.1 Self-inductance arrangements Substituting Eq. (4.26)into Eq.(4.24)gives (427) 2 The self-inductance is proportional to the cross-sectional area of the air gap Ao, and is inversely proportional to the length of the air gap,Substituting Eq. (4.26) into Eq. (4.24) gives 2 0 0 2 2 W  A L = （4.27） The self-inductance is proportional to the cross-sectional area of the air gap, A0 , and is inversely proportional to the length of the air gap,  . 4.6.1 Self-inductance arrangements