1.假设原电流是I,后来是I-0.3 则R1=7/I=4/(I-0.3),解得I=0.7A所以原袭磨先的功率是UI=4.9W,后来的是4*(0.7-0.3)=1.6W减少了3.3W.2.电流增加了0.1A设电阻是R,则0.3*0.3*R+1.4=0.4*0.4*R,R=20欧姆。原先电仔禅贺压是IR=6V,后来是念派0.4*20=8V,增加了2V