(1)P额=UI=6V×0.6A=3.6W;(2)∵I= U R ∴R= U I = 6V 0.6A =10Ω,灯泡的实际功率:P实= U R = (3V)2 10Ω =0.9W;(3)把它接在电压为9V的电源两端并使它正常发光,需要串联分压,另一个电阻分压U1=U总-U=9-6V=3V.则R串= U1 I = 3V 0.6A =5Ω.故答案为:3.6;0.9;串;5.