题干

如图所示,电源电压不变,灯泡L标有“6V 3W”(不考虑温度对灯泡电阻的影响) . 当开关S闭合,S1、S2断开,滑片P从b端滑到某一位置时,变阻器的电阻减小6Ω,电流表的示数变化0.1A,灯泡恰好正常发光;保持滑片P位置不变,闭合S1、S2,电流表的示数又变化了1.5A . 则当S1、S2都闭合时,调节滑片P,电路消耗的最小功率为(   )


A:2 W

B:10 W

C:15 W

D:20 W

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答案(点此获取答案解析)

D

同类题3

阅读表达 阅读下面的短文并用英语回答问题,并将答案写在答题卡上标有题号的横线上。

    The way we spend our time can be. divided into three groups,or jars(罐子).These would be the necessary tasks jar, the voluntary tasks jar and the happiness jar.

    Every day,we spend time filling the necessary tasks jar. We fill this jar with useful things,like making money,doing housework,buying food and paying bills. We then fill another jar with voluntary tasks like taking children to activities and cooking family meals. Those jars are very important,but we may not enjoy them. If we don't fill them each day,our family won't run properly.

    However, we often forget to fill the third jar—the happiness jar. This is the jar that we fill with activities that make us happy. Is your happiness jar sometimes empty at the end of the day? We all have days like that. Between doing all the necessary, and voluntary tasks,time flies by on some days,and before we know it,it is time for bed.

    That is why each day we try to fill our happiness jar. Most days,I fill mine by going to the ballroom dance(社交舞)class. Playing music is another way that I fill my happiness jar. This week,I was happy to take part in an orchestra(管弦乐队)practice at my church(教堂).At the end of the evening, my happiness jar was full.

    Consider how your time is spent. Try to find ways to achieve a balance. At the end of the day,hopefully we've done all we can to make sure that our happiness jar is filled.