题干

小明在做“测定小灯泡的电功率”的实验时,实验器材齐全并完好,其中:电源电压为4.5伏且不变,待测小灯泡L标有“2.5V”字样,滑动变阻器Rp有“20Ω 2A”和“50Ω 1A”两种规格可选。他正确串联实验器材,闭合电键,逐步移动滑片P的位置,并观察电压表的示数,当电压表的示数分别高于、等于、低于2.5伏时,分别观察电流表的示数,并将实验数据记录在右表中。


①请画出小明同学连接的实验电路图。____

②小明实验中选用的滑动变阻器的规格为____,理由是____

③请根据相关信息计算出小灯泡L的额定功率。(需写出计算过程)____

上一题 下一题 0.0难度 选择题 更新时间:2018-03-01 09:14:24

答案(点此获取答案解析)

,50Ω 1A,滑动变阻器两端电压为3伏时,滑动变阻器的阻值为25欧,大于20欧,0.4W

同类题4

阅读理解

    England continues to be one of the most popular tourist destinations in the world. London in particular is one of the most visited cities and draws people in with its appeal, history, and pubs. England's smaller cities, like Bath and Oxford, are equally as attractive with a lot of culture and fewer crowds. Liverpool, birthplace of The Beatles, has a rich musical history. The countryside has wonderful natural beauty. Here are some tips on traveling in England.

    Free museums—Public museums offer free admission in every city throughout England and the UK. It's a great way to learn about the country's most influential artists and history, and spend a rainy day without paying a cent.

    Book early—Book all transportation well in advance, even if you don't plan to use it. Fares can be around £2 with a little planning. The Megabus not only runs buses but also provides trains throughout England and is the best choice for cheap travel throughout the country.

    Pub food—Eating in England can be quite expensive, but for good cheap and filling meals, visit the local pubs, where you can get a good meal for less than £10. Besides, the pubs are a great way to meet people!

    Get a Taste of UK card—The Taste of the UK card offers up to 50% off at selected restaurants. You don't need to be an English to get the card, and you needn't pay the first month's membership fee, which is perfect for most travelers.

    Take a free walking tour—Many major cities in England offer free walking tours. They usually last a few hours and are a great way to see the city.