单项选择题
A.最大值 B.有效值 C.平均值 D.瞬时值
A.220V,300W B.110V,100W C.110V,60W D.110V,500W
A.达到铁芯高度的1/2 B.达到铁芯高典的1/3 C.达到铁芯高典的2/3 D.浸没铁芯和绕组