灯泡L1的电阻R1= U P1 = (6V)2 2W =18Ω；灯泡L2的电阻R2= U P2 = (12V)2 8W =18Ω；两电阻相等，并联后的电阻为R= R1 2 = 18Ω 2 =9Ω；在10min内整个电路做功为W= U2 R t= (6V)2 9Ω ×10×60s=2400J．故选A．
