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问题 实验题

（4分）（1）如图是探究“电流通过导体产生的热量与电阻的关系”为达到实验目的，选用的两电阻丝的阻值     （选填“相同”或“不同”）。通过观察_____________，可以知道电流产生的热量的多少。

（2）在探究“电流与电阻的关系”的过程中．小明把5Ω的电阻再分别换接10Ω、15Ω的电阻，重复实验，得到表一中三组数据．分析表一数据，可得出结论；保持电压不变时，导体中的电流跟导体的电阻成　 　比．小丽在做此实验时，每次只更换电阻，测得相应的电流值，如表二所示，根据表中数据，她无法得到与小明相同的结论，其原因是           

答案

（1）不相等；温度计示数上升的高低；（2）反，没有控制电阻两端的电压不变

题目分析：（1）由于电流所产生热量的多少与导体的电阻、电流的大小和通电时间有关，故想比较电热的大小与导体电阻大小的关系，必须用控制变量的思维来考虑：即需控制相同的电流和时间，利用不同的电阻才行；由于电热是无法捕捉的物理量，只能通过它表现出的性质来比较，本实验中用电热来加热液体，液体的温度会升高，故通过温度计升高的度数来体现出电热的多少；

（2）由表一中数据知，电阻两端的电压不变，电阻增大为原来的几倍，电流就减小为原来的几分之一，（也可以计算电阻与电流的乘积，发现乘积是不变的）所以可得：电压不变，电流与电阻成反比；在探究“电流与电阻的关系”的过程中必须保持电压不变才能得出与小明相同的结论，根据欧姆定律算出R两端电压：

U1=I1R1=0.3A×5Ω=1.5V，U2=I2R2=0.2A×10Ω=2V，U3=I3R3=0.15A×15Ω=2.25V，

显然三次实验中，电阻两端的电压均不相同，所以不能得出相同的结论的原因是没有控制电阻两端的电压不变．

选择题

下面四个比例尺中，最小的是[ ]

A、图上1厘米代表实际距离100千米

B、1/50000

C、五十万分之一

D、1：1000000
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问答题

Part 1


·Read the following passages, eight sentences have been removed from the article.
·Choose.from the sentences A-H the one which fits each gap.
·For each gap (1-8) mark one letter (A-H) on the Answer Sheet.
·Do not mark any letter twice.
Today’s career assumptions are you can get a lot of development, challenge and job satisfaction and not necessarily be in a management role.
A new malady is running rampantly in corporate America: management phobia. (1)
" I hated all the meetings," says a 10-year award-winning manager, "and I found the more you did for people who worked for you, the more they expected." (2)
With technology changing in a wink, you can never slack off these days if you’re on the technical side. (3)
In addition, the Dilbert factor is at work. With Scott Adams’s popular cartoon character— as well as many television sitcoms — routinely portraying managers as morons or enemies, they just don’t get much respect anymore.
Supervising others was always a tough task, but in the past that stress was offset by hopes for career mobility and financial rewards. (4)
But in today’s global, more competitive arena, a manager sits on an insecure perch. (5) There are far fewer rungs on the corporate ladder for managers to climb. In addition, managerial jobs demand more hours and headaches than ever before but offer slim, if any, financial paybacks and perks.
Furthermore, managers now must supervise many people who are spread over different locations, even over different continents. (6)
In an age of entrepreneurship, when the most praised people in business are those launching something new, management seems like an invisible, thankless role. (7)
Management layoffs have done much to erode interest in managerial jobs, of course. (8)
A. Many people don’t want to be a manager — and many people who are managers are, frankly, itching to jump off the management track — or have already.
B. It’s a rare person who can manage to keep up on the technical side and handle a management job, too.
C. Restructuring have eliminated layer after layer of management as companies came to view their organizations as collections of competencies rather than hierarchies.
D. They must manage across functions with, say, design, finance, marketing and technical people reporting to them.
E. I was a counselor, motivator, financial adviser and psychologist.
F. Employers are looking for people who can do things, not for people who make other people do things.
G. American Management Association surveys say three middle managers are laid off for every one being hired.
H. Along with a sizable pay raise, people chosen as managers would begin a nearly automatic climb up the career ladder to lucrative executive perks: stock options, company cars, club memberships, plus the key to the executive washroom.
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