[题目]把一个3 pF的平行板电容器接在9 V的电池上.(1)保持与电池的连接.两极板的距离减半.极板上的电荷增加还是减少?电荷变化了多少?(2)移去电池后两极板的距离减半.极板间的电势差增大还是减小?电势差变化了多少? 题目和参考答案——青夏教育精英家教网—

题目内容

【题目】把一个3 pF的平行板电容器接在9 V的电池上。

（1）保持与电池的连接，两极板的距离减半，极板上的电荷增加还是减少？电荷变化了多少？

（2）移去电池后两极板的距离减半，极板间的电势差增大还是减小？电势差变化了多少？

【答案】（1）电荷增加 2．7×10－11 C （2）电势差减小 4．5 V

【解析】（1）当电源与电容器一直连接时，电容器两极间电压保持不变，电容器原来带电荷量：Q＝UC＝9×3×10－12 C＝2．7×10－11 C

当两极板的距离减半时，C′＝2C＝6×10－12 F

电容器后来带电荷量：Q′＝UC′＝5．4×10－11 C

极板上电荷增加了ΔQ＝Q′－Q＝2．7×10－11 C

（2）移去电池，电容器上电荷量Q不变，由C′＝得电势差U′＝＝V＝4．5 V，由此可知距离减半时，极板间电势差减小。

故电势差改变量为ΔU＝U－U′＝4．5 V

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【题目】短文改错

假定英语课上老师要求同桌之间交换修改作文，请你修改你同桌写的以下作文。文中共有10处语言错误，每句中最多有两处。每处错误仅涉及一个单词的增加、删除或修改。

增加：在缺词处加一个漏字符号(/\)，并在其下面写出该加的词；

删除：把多余的词用斜线(\)划掉；

修改：在错词下画一横线，并在该词下面写出修改后的词。

注意：1. 每处错误及其修改均仅限一词；

2. 只允许修改10处，多者(从第11处起)不计分。

Last weekend, my classmate and I went on a camping trip near the river. It was not long distance, so we chose to get here by bike.

We started with early in the morning. On the way, we talked about that we saw around. It takes about half an hour to get to the place. On arriving, some girls sat down, had her breakfast and listened to the birds sings. Some admired the river while others drew pictures. My friends and I found a quietly place and went fishing. To our surprise, we got much fishes.

Time passed so quickly and we had to say goodbye. I enjoyed the pleasant or exciting trip.

【题目】短文改错

假定英语课上老师要求同桌之间交换修改作文，请你修改你同桌写的以下作文。文中共有10处语言错误，每句中最多有两处。错误涉及一个单词的增加、删除或修改。

增加：在缺词处加一个漏词符号（∧），并在其下面写出该加的词。

删除：把多余的词用斜线（\）划掉。

修改：在错的词下划一横线，并在该词下面写出修改后的词。

注意：

1. 每处错误及其修改均仅限一词；

2. 只允许修改10处，多者（从第11处起）不计分。

What is the most valuable thing in the world? Although the answer many vary from person to person, but as for me, reading books is most valuable than anything else. As old saying goes, “To open a book is always helpful. ”

First, books are our teachers. They introduce different kind of knowledge to us, include science and literature. Books are our friends either. With the valuable experience in them, books often helps us out when we meet difficulties. By increasing our knowledge and enlarge our experience, books lead us down the road to succeed. Therefore, to read more books is the best policy for we young students.

【题目】选词填空

用下列词组的适当形式完成下列句子。

fast asleep vary from … to… take sb. by surprise freeze over

draw up give birth to make one’s way take notice

have a gift for burn to the ground

1. The air temperature was well below freezing, and lakes and rivers __________.

2. Having spent the whole morning climbing Mount. Tai, the family were very tired and slowly ____________ to

the hotel.

3. He was lying ____________ on the sofa; it would be cruel to wake him.

4. His heart attack was so sudden that I think even the doctors were ____________.

5. The story The Pity of Zhongyong concerns a boy who _______________ writing poetry in his childhood.

6. The outbreak of H7N9 bird flu has really made the government sit up and ___________.

7. The film If You Are the One ______________ a TV show of the same name.

8. After a heated discussion, they __________ a plan to advertise their new product nationwide.

9. The bus was ___________, and at least 30 people burnt to death.

10. The land of Changbaishan ______ in height ____ 700 metres above sea level __ over 2,000 metres.

【题目】有一灯泡上标有“6 V 0．1 A”字样，现要测绘该灯泡的伏安特性曲线，有下列器材可供选用

A．电压表（0～5 V，内阻2．0 kΩ）

B．电压表（0～10 V，内阻3．0 kΩ）

C．电流表（0～100m A，内阻2．0 Ω）

D．电流表（0～6 A，内阻1．5 Ω）

E．滑动变阻器（30 Ω，2 A）

F．滑动变阻器（100 Ω，0．5 A）

G．学生电源（直流9 V）及开关、导线等

（1）实验中所用的电压表应选________，电流表应选________，滑动变阻器应选________。

（2）画出实验电路图，要求电压从零开始测量。

（3）根据你的实验电路，将图中所示的器材连成实验电路。

（4）该同学描绘出的IU图像应是图中的________。

【题目】A

The first ancient Olympic Games for which we still have written records were held in 776 BC. Coroebus won the only event at the Olympics. This made him the very first Olympic champion in history. Then they grew and continued to be played every four years. In 393 AD, the Roman emperor Theodosius Ⅰ, a Christian, announced to end the Games because of their pagan (异教的) influences.

About 1,500 years later, a young Frenchman named Pierre de Coubertin began their revival (恢复). In 1892 Coubertin first brought forward his idea to revive the Olympic Games but failed.

Two years later, Coubertin organized a meeting with 79 delegates (代表) who represented nine countries. At this meeting he got what he wanted. All the delegates at the conference voted for the Olympic Games. They also decided to have Coubertin set up an international committee to organize the Games. This committee became the International Olympic Committee (IOC) and Demetrious Vikelas from Greece was selected to be its first president. Athens was chosen for the revival of the Olympic Games and the planning was begun.

The very first modern Olympic Games opened in the first week of April, 1896. Since the Greek government had been unable to afford a stadium, a rich Greek architect, Georgios Averoff, donated one million drachmas (over $100,000) to repair the Panathenaic Stadium, originally built in 330 BC.

Since the Games were not well publicized internationally, contestants (选手) were not nationally chosen but rather came individually and at their own expense. Some contestants were tourists who happened to be in the area during the Games.

【1】What would be the best title for the passage?

A. The History of the Olympics

B. How Coubertin Set up IOC

C. The First Modern Olympic Games

D. Great Changes in the Olympic Games

【2】 Coubertin held a most important meeting with 79 delegates in______________.

A. 1500 B. 1892

C. 1894 D. 1896

【3】 Who offered money to help the first modern Olympic Games?

A. Demetrious Vikelas.

B. Coroebus.

C. Pierre de Coubertin.

D. Georgios Averoff.

【4】At the first modern Olympic Games, ______________.

A. winners were given money as prize

B. IOC invited contestants to tour Greece

C. there were no strict rules for being a contestant

D. many countries chose some athletes to compete

【题目】如图所示是一种利用电磁原理制作的充气泵的结构示意图。其工作原理类似于打点计时器，当电磁铁通入电流时，可吸引或排斥上部的小磁铁，从而带动弹性金属片对橡皮碗下面的气室施加力的作用，达到对外充气的效果。请回答以下问题：

（1）当电流从电磁铁的接线柱a流入时，发现吸引小磁铁向下运动，则电磁铁的上端为________极，小磁铁的下端为________极。

（2）你认为这种充气泵是利用直流电好，还是利用交流电好？答案：________

（3）缠绕电磁铁用的铁芯可分为硬磁性材料和软磁性材料。硬磁性材料在磁场撤去后还会有很强的磁性，而软磁性材料在磁场撤去后就没有明显的磁性了。你认为这种铁芯最好用________材料制作。

【题目】在某些恒星内，3个α粒子结合成一个，原子的质量是12．000 0u，原子的质量是4．002 6u，已知1u＝1．66×10－27kg，则（）

A．反应过程中的质量亏损是Δm＝0．007 8u

B．反应过程中的质量亏损是Δm＝1．29×10－29kg

C．反应过程中放出的能量是7．266MeV

D．反应过程中放出的能量是1．16×10－19J

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