3) 500uA x 4k = 10A x R, R=0.2欧.4) R1 R2 R3 等如 R1+ R2//R3 = 16 + 4 =20欧 , 20欧//R4 =20//20=10欧,I= 12/(10+2)=1A. P4 = I^2 R4 = 1/2 x 1/2 x 20 = 5w.
1) 40=10i2+5+5i1,7=2i2+i1.(1) 25=10i3-5-10i2,6=2i3-2i2.(2) i1=i2+i3.(3) (1)+(2) 13=2i3+i1, 代入(3) 13=3i3+i2,再乘2 , 26=6i3+2i2 联立(2) 32=8i3,i3=4A,R3电流向下. 6=8-2i2,2=2i2,i2=1A,R2电流向下. i1=1+4=5A,R1电流向上.2) 10=5i1+10i3+5i1,1=i1+i3.(1) 5=10i3-i2.(2) i1=i3+i2 .(3) (2)+(3) 5=11i3-i1 联立(1) 6=12i3, i3=0.5A. 5=10(0.5)-i2,i2=0. i1=0.5+0 =0.5A.
(2) 25v电压源串5欧变为 5A电流源并5欧向上, 2个电流源相加=10A,并(5欧并20欧)=4欧, I= 12欧串24欧支路电流 = 10 x 4/(4+12+24) =1A. U(24欧) = 1x24=24v.