A.各相負(fù)載上電流對(duì)稱電壓不對(duì)稱 B.各相負(fù)載上電壓、電流都對(duì)稱 C.各相負(fù)載上電壓對(duì)稱電流不對(duì)稱 D.各相負(fù)載上電壓、電流都不對(duì)稱
如圖所示電路,當(dāng)開(kāi)關(guān)S斷開(kāi)時(shí),A點(diǎn)電位VA=()V;當(dāng)開(kāi)關(guān)S閉合時(shí),A點(diǎn)電位VA=()V。
A.4V和0V B.4V和4V C.1.3V和0V D.0V和0V
A.R總=R1+R2 B.R總=R1/R2 C.R總=R1*R2/(R1+R2) D.R總=1/R1+1/R2