小青怪
幼苗
共回答了14个问题采纳率:100% 举报
这个图怎么不放放正?
R345 =R4//R5+R3
=900//300+775
=1000 Ω
Uab = R345 * I3=1000 Ω * 50 mA =50 v
所以:
(1)I2 = 50/R2=50v /2000Ω =25 mA
I1 = I - I2 - I3 = 100 - 50 - 25 =25 mA
UR4=I3*(R4//R5)=50 mA * (900//300)=50 mA * 225Ω = 11.25 V
I4 = UR4/R4 = 11.25 / 900 =12.5 mA
I5 = I3 -I4 = 50 - 12.5 = 37.5 mA
(2)I1*R1=Uab
R1 = Uab/I1=50 v/25mA = 2000 Ω
或者根据并联的分流作用,因为I1 = I2,端电压相等,所以R1=R2
(3)Rab = 1000 Ω//R1//R2 = 1000//2000//2000=500Ω
(4)Pab=I*Uab=100 mA * 50 V = 5W
1年前
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