Question

电学综合计算一道当电阻R3和电阻R1串联时消耗的电功率是0.45W,当电阻R3和电阻R2串联时电功率是0.8W,已知R3

Answer 1

当电阻R3和电阻R1串联时消耗的电功率是0.45W,

P1=U^2/(R1+R3)= 0.45W

当电阻R3和电阻R2串联时电功率是0.8W

P2=U^2/(20+R2)=0.8W

R3=20Ω,R1:R2=2:1

P1/P2=(20+R2)/(2R2+20)=0.45/0.8=9/16

R2=70Ω

电源电压

U^2=6*2^1/2V