Q'- dl' d dl Mcos0 dl Msino 三d=Mxe dl dI'=Mdl cos0=M.dl ordW'=adl=M×endl I d d ′ α′ = n eM r r r ⇒α′ ×= lMlMI r r ′ = θ ⋅= dcosdd = M cosθ = M sinϕ ddor dleMlI nr r ′ =α′ ×=