A.I=r²H/2; B.I=5²r²H; C.I=10²r²H; D.I=π²r²H/2
A.剩磁法; B.復(fù)合矢量磁化法; C.連續(xù)法; D.波動(dòng)法
A.0.75mm; B.0.2mm; C.0.1mm; D.1.0mm