W=U^2/R1*10min=U^2/R2*20min
化简得:R2=2R1
串联:R总=3R1
W=U^2/R1*10min=U^2/R总*t
10/R1=t/3R1
得t=30min
并联:R总=(U1*U2)/U1+U2=2/3R1
W=U^2/R1*10min=U^2/(2/3)R*t
t=20/3min
W=U^2/R1*10min=U^2/R2*20min
化简得:R2=2R1
串联:R总=3R1
W=U^2/R1*10min=U^2/R总*t
10/R1=t/3R1
得t=30min
并联:R总=(U1*U2)/U1+U2=2/3R1
W=U^2/R1*10min=U^2/(2/3)R*t
t=20/3min