如圖所示正弦交流電的初相位是()
A.π/6 B.-(π/6) C.7π/6 D.π/3
如圖所示二端網(wǎng)絡(luò),等效為一個電源時的電動勢為()
A.8V B.4V C.2V D.6V
A.電力制動 B.反接制動 C.能耗制動 D.機(jī)械制動