试题与答案

将没有闭合的多匝线圈置于仅随时间变化的磁场中,线圈平面与磁场方向垂直,下列表述正

题型:选择题

题目:

将没有闭合的多匝线圈置于仅随时间变化的磁场中,线圈平面与磁场方向垂直,下列表述正确的是(  )

A.感应电动势的大小与线圈的匝数无关

B.穿过线圈的磁通量变化越快,感应电动势越大

C.产生的电动势属于动生电动势

D.既不产生感应电流又不产生感应电动势

答案:

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题型:阅读理解

When the Farnsworth family moved to their new farm in 1919, eleven-year-old Philo was surprised to find it wired for electricity. This unusual circumstance contributed to his fate — to become an important inventor of the twentieth century.

By thirteen, Farnsworth had become a self-taught electrical engineer. He was able to fix the farm’s generator(发电机)when none of the adults could. In 1922, he read an article about a new idea of John Baird, a Scottish scientist, who had been working with the cathode ray tube (阴极射线管) for the transmission of electronic pictures and wanted to attempt it himself.

Farnsworth studied everything he could find on the subject. Although many older engineers with money backers were already developing television, Farnsworth made a bold decision — he was going to perfect a working model of it before anybody else.

In college, Farnsworth continued his research with cathode ray and vacuum tubes, but the death of his father, the only money maker in the family, forced him to give up this research and find a job. His first job was for George Everson, with whom Farnsworth discussed his dream of television. While acknowledging the achievements of those who came before, Farnsworth thought that he could get closer. Everson agreed to risk $6,000 for the research.

Backers came in 1927 to see the first American television, one year after Baird’s. They were astonished to see the image of a single white line resolve itself on the screen before them, and agreed that this new invention was worth putting money into.

In 1930, Farnsworth won a patent (专利权) for his all-electronic TV. By the time he died, he had earned over 300 American and foreign patents for electronic and mechanical devices.

小题1:When Farnsworth was at a young age, he _______

A.had to drop out of school to help on the family farm

B.was sent to school to study electrical engineering

C.wanted to be the first person to invent the television

D.had shown a surprising ability in the electrical field小题2:What difficulty did Farnsworth meet when he first began his research on the television?

A.His parents didn’t support his work.

B.He didn’t have enough knowledge in this field.

C.He didn’t have enough money for his research.

D.No one was interested in this research.小题3:How old was Philo Farnsworth when he invented the first American television?

A.11.

B.13.

C.19.

D.22.小题4:From the passage, we can learn that Farnsworth is ______.

A.the first person who worked for the transmission of electronic pictures

B.an inventor who improved on somebody else’s idea

C.an inventor who always came up with an original idea

D.a person who earned over 300 American patents for electronic devices

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题型:解答题

分析说明题:

请同学们认真阅读下列材料,回答问题:

材料一:中国营养学会将我国成年人钙供给量定为0.8克/天,处于生长发育旺盛的青少年对钙的需求量更高,但我国绝大多数人远未达到这一标准.据调查显示,我国95%的儿童存在不同程度的缺钙.

材料二:下面是不同食物中钙的相对量.(单位:mg/100克食物)

食物品种大米馒头瘦肉青菜马铃薯牛奶豆腐
含钙量3.630.06.0102.030.011.0100.0160.0
材料三:少年儿童骨内无机物含量接近2/3,实验证明组成骨的无机物主要是钙盐,使骨脆硬.

(1)材料显示:钙是______的重要组成成分,少年儿童缺少钙易患______病.

(2)人体摄入的钙等无机盐主要是在______处被吸收的.

(3)王刚同学某日的食谱如下:(单位:克)

食物馒头青菜豆腐瘦肉
质量500500100100
请计算一下王刚同学该日摄入钙的质量是______克.参照以上数字,仅从人体对钙的需求考虑,谈谈教育部号召开展“豆奶工程”的意义是______.

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