如图，R1=6Ω，U2=3V，总电压为7V。求：1、电阻R1两端的电压 2、电路中的电流 3、电阻R2的阻止

U1=U-U2=7-3=4V I=I2=I1=U1/R1=4/衫厅6=2/碧誉3欧 R2=U2/I2=3/ U1=U-U2=7-3=4V I=I2=I1=U1/R1=4/衫厅6=2/碧誉3欧 R2=U2/I2=3/2/悔塌段3=4.5欧

7-3=4V;
4/6=2/3A;
3/(2/3)=4.5.

1.U1=U总-U2=7V-3V=4V
2.I1=U1／R1=4V／6Ω=0.67A，I1=I总稿旁=0.67A
3.U1／R1=U2／键如橡R2=4V／橡源6Ω=3V／R2，R2=4.5Ω

1.U1 = U总-U2 = 7V-3V = 4V
2.I总 = I2 = I1 = U1／R1 = 4V／贺哗慎6Ω = 0.67A
3.R2 = U2/芦神I2 = 3V /禅敬 (2/3)A = 4.5Ω