phân tích mạch R1nt[(R2ntR3)//R4]
R23=R2+R3=40+30=70(ôm)
R234=R23.R4/R23+R4=70.40/40+70=280/11(ôm)
=>Rtd=R1+R234=40+280/11=720/11(ôm)
=>Uab=720/11.1,2=864/11(V)
có R1ntR234
=>I1=I234=I=1,2(ampe)
=>U234=1,2.280/11=336/11(ôm)
vì R23//R4
=>U23=U4=U234=336/11 ôm
=>I4=336/11:40=42/55(ampe)
R2ntR3=>I2=I3=I23=U23/R23=336/11:70=24/55(ampe)