分析甲图的L1
P1=I²R1=U²/(R1+R2)² × R1
分析乙图的L1
P1'=U²/R1
∴P1/P1'=R1²/(R1+R2)²=9W/25W=9/25
∴R1/(R1+R2)=3/5
∴2R1=3R2
则,题目求的P甲=U²/(R1+R2)=5U²/2R2
P乙=U²/R1+U²/R2=2U²/3R2+U²/R2=5U²/3R2
∴P甲:P乙=(5/2):(5/3)=3:2
分析甲图的L1
P1=I²R1=U²/(R1+R2)² × R1
分析乙图的L1
P1'=U²/R1
∴P1/P1'=R1²/(R1+R2)²=9W/25W=9/25
∴R1/(R1+R2)=3/5
∴2R1=3R2
则,题目求的P甲=U²/(R1+R2)=5U²/2R2
P乙=U²/R1+U²/R2=2U²/3R2+U²/R2=5U²/3R2
∴P甲:P乙=(5/2):(5/3)=3:2