问题 填空题

甲、乙两个验电器,如题图所示,已知甲验电器的箔片带负电,乙不带电,用一根带有绝缘柄的金属棒连接两个金属球,会看到验电器乙的箔片______,说明______.

答案

验电器是利用同种电荷相互排斥的原理制成的;连接的瞬间,甲带的负电减少,说明电子从甲到乙移动,验电器甲带的负电减少,金属箔片张角变小,而乙由原来的不带电到带上负电,所以乙验电器会出现张角,这说明有电子从甲转移到乙;

故答案为:张角;有电子从甲转移到乙.

单项选择题
阅读理解

The two largest islands of the British Isles are Great Britain and Ireland. England, Wales and Scotland together form Great Britain. Scotland, lying in the northern part of Great Britain and bordering(接壤)England on the south, is half the size of England and Wales, having an area of about 76 000 square kilometers. Most of Northern Scotland is mountainous area known as the Scottish Highlands. In the center of Scotland there are the Central Low-lands, and the south is waving, hilly area known as the Southern Uplands which rise to 800m. There are many rivers in Great Britain, but they are not very long. The rivers which run to the east are longer than the ones which run to the west.

In Scotland the main rainy winds come from the Atlantic Ocean. The west part is wet with an average(平均) rainfall of up to 200cm while the east is dry with about 75cm. The winters are cold with an average January temperature of 4℃. The summers are cold and warm but rarely hot.

1. This passage mainly tells us____ .

A. how many parts form Great Britain

B. the positions of England, Wales and Scotland

C. the areas of Great Britain

D. Something about Scotland

2. England lies____ .

A. in the south of Great Britain          B. to the south of Scotland

C. to the north of Wales                D. in the north of Scotland

3. This passage also tells us____ .

A. the population of Great Britain        B. the history of England and Wales

C. the size of Scotland                 D. the position of Northern Ireland

4. The Central lowlands_____ .

A. lie between the Scottish Highlands and the Southern Uplands

B. lie to the north of Scottish Highlands

C. lie to the south of the Southern Uplands

D. border England on the south

5. The writer says that in Scotland there is more rain____ .

A. in the Highlands than in the Southern Uplands     B. in the west part than in the east

C. in the Central Lowlands than in the Highland      D. in the east than in the west