例2 P U P 已知:U1=10V,I1=5A,U2=0,2=1AU2=10V求U 解 U11+U2(-12)=U1(-1)+U2l2 U1=2l1 U U1x=U/1(-1)+U2l2 U1=1v 10 U=U1×(-5)+10×1例2. 解 P –+U1 –+U2 I2 I1 P –+ –+ 2  1 U 2 U 1 I 2 I 已知： U1=10V, I1=5A, U2=0, I2=1A 2 = 10 V U 1 .  求 U ( ) ( ) 2 2 1 2 1 2 1 1 U I U I U I U I     + − = − + 1 2 1   U = I 1 = 1V. U ( ) 2 1 1 2 2 1 1 U I U I U U     = − + ( 5) 10 1 2 10 1 1  =  − +    U U