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问题: R1=R2=2欧,R4=4欧,r=1欧.当电键K闭合时,伏特表V1和V2的读数分别为

R1=R2=2欧,R4=4欧,r=1欧.当电键K闭合时,伏特表V1和V2的读数分别为8V,6V,若将V1V2分别换成电流表A1
A2,两电流表读数是多少?
答案:A1,30/11 A2,20/11
给出过程,O(∩_∩)O谢谢

解答:

原来,大家串联,总电阻R3+9Ω
V1测量R1+R2分压
V2测量R2+R3分压
ε *4/(R3+9) =8 ..........(1)
ε *(R3+2)/(R3+9) =6 ........(2)
(1)/(2) ==>4/(R3+2)=8/6 ===>R3=1Ω ==>ε =20V

后来,R1R2R3并联,再串联R4和r
R1R2R3并联 =R
则 1/R =1/R1 +1/R2+1/R3 =2 ==>R =1/2
全电路总电阻 =1/2+4+1 =11/2
R1R2R3并联,它们分压U=ε *(1/2)/(11/2)=20V/11
R1R2R3并联的总电流I =U/R =40A/11
它们分流10A/11 ,10A/11,20A/11
A1测R2+R3的电流和 =30A/11
A2测R1+R2的电流=20A/11