设电源电压为U,串联时,电流相等,由P=I²R可得I²R1=3 ,I²R2=6 两式相除可得,R1/R2 =3/6 =1/2串联电路电压与电阻成正比,有U1/U2 =1/2,U2=2U1则U=U1+U2=3U1,即U1=U/3 ,同理,U2=2U/3由公式P=U²/R ...