题目

Save the Game    The basketball final between Perfect School and Sunrise School has entered white-hot stage. There are only fifteen seconds left. Sunrise School is one point ahead. Mitchell, who is one of the best players of Perfect School, is now controlling the ball. The students are extremely excited. They cannot help standing up and shouting, “Go! Mitchell!”Other teammates also encourage Mitchell, “Take a shot, boy!”    Mitchell knows it will be the last shot. He hesitates (犹豫) and falls into careful thinking. He imagines that he shoots from the halfway line. The hal如图所示，标有“6V 3W”字样的小灯泡与最大阻值为18Ω的滑动变阻器R1串联，当变阻器连入电路中的电阻为8Ω时灯正常发光（不考虑灯泡电阻受温度影响，电源电压不变）．求：（1）灯泡电阻；（2）当滑动变阻器滑片移到阻值最大处时，灯泡的实际功率是多少？（结果可保留分数）