A.對(duì)調(diào)兩繞組之一的首末端 B.同時(shí)對(duì)調(diào)兩繞組的首末端 C.對(duì)調(diào)電源的極性 D.對(duì)調(diào)電容的兩端
A.增大 B.減小 C.不變 D.與磁極數(shù)無(wú)關(guān)
A.恒定磁場(chǎng)B.脈動(dòng)磁場(chǎng)C.合成磁場(chǎng)為零D.旋轉(zhuǎn)磁場(chǎng)