A.50Hz B.20Hz C.2Hz D.4Hz
A.1 B.0 C.大于1 D.大于0且遠(yuǎn)小于1
A.由于無外部電源給轉(zhuǎn)子供電,故無電流 B.由于有外部電源給轉(zhuǎn)子供電,故有電流 C.由于無電磁感應(yīng),故無電流 D.由于有電磁感應(yīng),故有電流