(1)∵R1、R2并联,∴通过电阻R1的电流:I1= U1 R1 = U R1 = 6V 20Ω =0.3A;(2)干路电流:I=I1+I2=0.3A+0.6A=0.9A,R1和R2的总电阻:R= U I = 6V 0.9A ≈6.7Ω;(3)电阻R1消耗的电功率:P1=UI1=6V×0.3A=1.8W.答:(1)通过电阻R1的电流是0.3A;(2)R1和R2的总电阻约为6.7Ω;(3)电阻R1消耗的电功率是1.8W.