R1的电阻为20欧,当开关S闭合后,电流表A的示数为2.7A,电流表A1的示数为1.8A.
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  • (1)电源电压U=I1xR1=1.8A×20Ω=36V.通过电阻R2的电流I2=I-I1=2.7A-1.8A=0.9A,电阻R2的电阻值R2=U/I2=36V/0.9A=40Ω.(2)P1=I1xI1xR1=1.8Ax1.8Ax20Ω=64.8wp2=I2xI2XR2=0.9Ax0.9Ax40Ω=32.4WP1:P2=2:1答:电阻R2的电阻值为40Ω.电阻R1与R2的电功率之比 2:1