一道物理题。。 5
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P在A点时,电路中电流I=U/(RL+RA),V2示数是U2=IRA=[U/(RL+RA)]*RA
P在B点时,电路中电流I'=U/(RL+RA+10Ω),V2示数是U2'=I'(RA+10Ω)=[U/(RL+RA+10Ω)]*(RA+10Ω)
上面两式相比得[RA/(RA+RL)]/[(RA+10Ω)/(RL+RA+10Ω)]=2:3(1)
P在B点时,V1和V2示数之比是1:3,根据串联分压关系得RL/(RA+10Ω)=1:3 (2)
解(1)(2)两式得RL=5Ω
P在B点时,电路中电流I'=U/(RL+RA+10Ω),V2示数是U2'=I'(RA+10Ω)=[U/(RL+RA+10Ω)]*(RA+10Ω)
上面两式相比得[RA/(RA+RL)]/[(RA+10Ω)/(RL+RA+10Ω)]=2:3(1)
P在B点时,V1和V2示数之比是1:3,根据串联分压关系得RL/(RA+10Ω)=1:3 (2)
解(1)(2)两式得RL=5Ω
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