电功率=电压*电流,W=U*I,因为R=U/I,可以推出W=I^2*R=U^2/R.以你所说,若电阻恒定,很容易比出电压的平方.
一个电器并联电阻的总阻值的倒数,等于各并联电阻阻值的倒数和,1/R总=1/R1+1/R2+1/R3+……+1/Rn 若只两电阻并联,1/R总=1/R1+1/R2=（分母通分）R2/R1*R2+R1/R1*R2=（R1+R2）/R1*R2,即R总=R1*R2/R1+R2 电功率=电压*电流,W=U*I,因为R=U/I,可以推出W=I^2*R=U^2/R.以你所说,若电阻恒定,很容易比出电压的平方.
一个电器并联电阻的总阻值的倒数,等于各并联电阻阻值的倒数和,1/R总=1/R1+1/R2+1/R3+……+1/Rn 若只两电阻并联,1/R总=1/R1+1/R2=（分母通分）R2/R1*R2+R1/R1*R2=（R1+R2）/R1*R2,即R总=R1*R2/R1+R2