A.減小磁阻和銅損 B.減小磁阻和鐵損 C.減少渦流和剩磁 D.減少磁滯和矯頑力
A.1/700 B.1/1000 C.1/900 D.1/800
A.300-50mm B.500-80mm C.200-300mm D.100-200mm