(1)電流$I=\frac{U_{2}}{R_{2}}=\frac{6\ \text{V}}{60\ \Omega}=0.1\ \text{A}；$
(2)$R_{1}$兩端電壓$8\ \text{V}-6\ \text{V}=2\ \text{V}，$$R_{1}=\frac{2\ \text{V}}{0.1\ \text{A}}=20\ \Omega；$
(3)電流0.2 A時，總電阻$R_{\text{總}}=\frac{8\ \text{V}}{0.2\ \text{A}}=40\ \Omega，$$R_{2}=40\ \Omega-20\ \Omega=20\ \Omega，$電壓表示數(shù)$U=0.2\ \text{A}\times20\ \Omega=4\ \text{V}。$
