问题 填空题

如教材图8.5-3所示,滑动变阻器的作用是______.实验证明,______的保险作用较好,实验中保险丝和铜丝中的电流______,通电时间______,只有______不同,这采用的研究方法是______.

答案

(1)在实验中滑动变阻器的作用是改变电路中的电流,改变电流产生热量多少.

(2)保险丝和铜丝串联在电路中,通电时间相同,电流相同,保险丝先熔断,电流在保险丝上产生的热量不同,是因为保险丝和铜丝的长度和横截面积相同,材料不同造成的.

(3)电流产生的热量跟电流大小、电阻大小、通电时间有关.探究电流产生热量跟电阻大小时,控制电流大小和通电时间不变,这种方法是控制变量法.

故答案为:改变电路中的电流;保险丝;相同;相同;材料;控制变量法.

阅读理解

Most American families like to have a vacation in summer. Summer is a good season for vacation. It is often hot in July and August.

Children do not go to school in those two months. Some people like to stay at home, read books, or watch TV. Many families take their lunch to eat at a place with many trees or a nice lake.

Some people have enough time and money to travel to other countries like France, Japan and Australia. They usually fly to these countries. Many families travel by car or train to see interesting places in their own countries. Their favorite cities are New York, Chicago, Miami, San Francisco and Los Angeles.

Not everyone likes to go to busy cities. Some families travel to mountains or beautiful valleys.

根据短文内容,从A、B、C、D四个选项中选择正确答案,并将其字母代号填入答题卷相应空格内。(共5小题,每小题1分,满分5分)

小题1:       is a good season for vacation.

A.Spring

B.Summer

C.Autumn

D.Winter小题2:Many people don’t         during their vacation.

A.read books

B.travel

C.watch TV

D.go to work小题3:Many families like to have their lunch       during their vacation.

A.in the office

B.near a cinema

C.near a big factory

D.near a nice lake小题4:If you have        , you can travel to other countries.

A.money and friends

B.friends and time

C.money and time

D.food小题5:Which of the following is NOT true ?

A.Summer vacation is about two months long.

B.Some people usually go to other countries to travel.

C.Everyone likes to travel to busy cities.

D.It’s often hot in July and August in America.

问答题 简答题