bai 4.106
(r1;r2;r3)=(15;10;12)
U=12v
a)R4=12
Ra~0; Uac=Uad ; Ucb=Udbb
R12=15.10/(15+10)=6
R34=12.12/(12+12)=6
R1234=6+6=12
Rtd=12
Im=12/12=1(A)
Uad=Im.r12=6v
Ir1=6/15=2/5
Ir2=3/5
ir4=6/12=1/2
ir3=1/2
g/s dong di tu C--D
ir1=ir3+Icd
Icd=ir1-ir3=2/5-1/2=(4-5)/10=-1/10(A)
Icd=(-)=> chung to rang dieu g/s sai
=>chi so Ampe 0,1(A) dong tu Dden C
...
b) thay so ...thoi (mach ko doi)
c)
Ia=0,2 (+) C-->D
tai C
i1=ia+i3
tai D
i2+ia=i4
<=>he
i1-i3=0,2(1)
i4-i2=0,2(2)
i1+i2=i3+i4=Im =f(r4)(a)
Uac=I1.r1
UcB=I3.r3
15i1+12i3=12(3)
(1).12+(3)=>(12+15)i1=(12.0,2+12)
i1=(12.0,2+12)/27=1,6/3(A)
i3=1,6/3-0,2=1/3(A)
Uad=i2.r2
Udb=i4.r4
10.i2+r4.i4 =12(4)
(2).10+(4)
(r4+10)i4=2+12=14
i4=14/(r4+10) (b)
(a)&(b)=>1/3 +14/(r4+10)=Im(c)
Uab/rtd
Im=12.(r4+12)/(3.6r4+6.12)=(2r4+2.12)/(3r4+12)(d)
(c)&(d)
1/3 +14/(r4+10)=(2r4+2.12)/(3r4+12)
tu giai tiep pt