解答解:(1)当开关S1S1闭合、S2断开,电路稳定时,R2与R3串联,P1=E2R2+R3+r=2WP1=E2R2+R3+r=2W 当开关S1、S2都闭合,电路稳定时,电路中R1与R2并联后与R3串联,R并=R1R2R1+R2=3×63+6=2ΩR并=R1R2R1+R2=3×63+6=2Ω P2=E2R并+R3+r=4WP2=E2R并+R3+r=4W ...