H B 证-L N H=n/ B chuN m=|B·dS=BS=AMV y=N8 AI L-y=LN ZS=m27(下一页)S l μ I l N H = nI = I l N B H  =  = S l NI B dS BS S m   = • = =    S l N I N m 2   =  = lS n V l N I L 2 2 2    = = = （下一页） H B Ψ L I  m