题干

如图是探究“电流与电阻的关系”的实验电路图,电源电压保持6V不变,滑动变阻器的规格为“20Ω 1A”.实验中,先在a、b两点间接入10Ω的电阻,闭合开关S,移动滑动变阻器的滑片P,使电压表的示数为4V,记下此时电流表的示数,接着需要更换a、b间的电阻再进行两次实验,为了保证实验的进行,应选择下列的哪两个电阻()


A:20Ω和50Ω

B:40Ω和60Ω

C:20Ω和40Ω

D:20Ω和60Ω

上一题 下一题 0.0难度 选择题 更新时间:2019-03-06 03:17:21

答案(点此获取答案解析)

C

同类题5

阅读理解

    Qibao Ancient Village

    Qibao, located in the center of Minhang District, Shanghai, is a village with a history of one thousand years. In the village, wine and tea are served on old-fashioned square tables together with long benches, long-mouth copper pots and flat-end chopstick used. The most famous snacks in old Shanghai are square pastry, rice wine and steamed salted pork in wine.

    Telephone: 021-21087225

    Entrance Ticket: 45 yuan per all-in-one ticket (preferable price of 30 yuan is available now), covering almost all tourist attractions inside the village.

Jinshan Village of Farmer Painting

    Villagers skillfully make good use of folk arts such as printing and dyeing, embroidery (刺绣), wood carving. They take the various folk customs and the busy scenes of labor of villagers in the lower Changjiang valley as the theme of paintings and create farmer paintings in a simple style.

    Telephone: 021-57355555

    Entrance Ticket: 30 yuan/person

    Merry Countryside Tour in Zhonghua Village

    The village provides tourists with accommodations, tours, chess, cards, fitness and entertainment through renting out separate farmhouse and sells tourist products and agricultural by-products related to the merry countryside tour.

    Telephone: 021-57395433

    Entrance Ticket: Free

    Pudong Lingkong Agric Gardening

    It is one of Shanghai countryside tour scenic spots, which features art of teapots, crop plantation and export. The Geological Science Popularization Hall stores up tens of thousands of rare stones collected all over the world.

    Telephone: 021-33935557

    Entrance Ticket: 50 yuan/person