（7分）小明利用实验探究通过电阻的电流跟电阻两端电压的关系。_爱下问搜题

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问题实验题

（7分）小明利用实验探究通过电阻的电流跟电阻两端电压的关系。

（1）请你根据图甲所示的电路图用笔画线代替导线，将图乙中的器材连接起来。要求：变阻器滑片向右移动时，电流表示数变小，导线不能交叉。

（2）小明连接好电路后，闭合开关，发现无论怎样移动滑片P，电流表示数始终为0，电压表示数约6V，则电路中出现的故障可能是。

（3）小明排除故障后继续实验，通过调节滑动变阻器，改变定值电阻R两端的电压，测得电流、电压的值如表。分析表中的数据可以得出结论：。

定值电阻	实验次序	电压U/V	电流I/A
R＝10Ω	1	3.0	0.3
	2	4.5	0.45
	3	6.0	0.6

（4）小明将电阻换成一个额定电压为2.5V，阻值约为10Ω的小灯泡，进行“测量小灯泡的额定电功率”的实验：为了使实验更准确，需要对电路连接进行改进，你的改进是____________________，实验时调节滑动变阻器的滑片使电压表的示数为2.5V时，电流表的示数如图丙所示，其读数为 A，则小灯泡的额定功率是 W。

答案

（1）如图

（2）电阻R断路（3）电阻一定时，通过导体的电流与导体两端的电压成正比（4）电压表换0-3V的量程，电流表换0-0.6A的量程 0.24 0.6

题目分析：（1）变阻器滑片向右移动时，电流表示数变小，电阻变大，故下端接左下接线柱，由表知通过电路中的电流小于0.6A，故电流表选用0到0.6A量程，如图所示。（2）由题意知，电流表无示数说明电路某处发生断路，再由电压表示数为6V知，与电压表并联的电阻R发生断路。（3）由表中数据可知，控制的是电阻不变，探究电流与电压的关系，故得出的结论是：电阻一定时，通过导体的电流与导体两端的电压成正比。（4）由题意知，小灯泡的额定电压为2.5V，小于3V，通过电路中的电流约为0.25A，小于0.6A，故应将电压表换0-3V的量程，电流表换0-0.6A的量程；由丙知通过灯泡电流为0.24A，则小灯泡的额定功率为P=UI=2.5V×0.24A=0.6W。

多项选择题

影响技术转移成功的客观规律主要有（）。

A.技术转移的梯度最小律

B.技术转移的信息传递律

C.技术转移的人才载体律

D.技术转移的适用律

E.技术转移的系统律

单项选择题

Passage Two

Americans usually consider themselves a friendly people. Their friendships, however, tend to be shorter and more casual than friendships among people from other cultures. It is not uncommon for Americans to have only one close friend during their lifetime, and consider other "friends" to be just social acquaintances. This attitude probably has something to do with American mobility and the fact that Americans do not like to be dependent on other people. They tend to "compartmentalize" (划分) friendships, having "friends at work", "friends on the softball team", "family friends", etc.
Because the United States is a highly active society, full of movement and change, people always seem to be on the go. In this highly charged atmosphere, Americans can sometimes seem brusque (无礼的) or impatient. They want to get to know you as quickly as possible and then move on to something else. Sometimes, early on, they will ask you questions that you may feel are very personal. No insult is intended; the questions usually grow out of their genuine interest or curiosity, and their impatience to get to the heart of the matter. And the same goes for you. If you do not understand certain American behavior or you want to know more about them, do not hesitate to ask them questions about themselves. Americans are usually eager to explain all about their country or anything "American" in which you may be interested. So much so in fact that you may become tired of listening. It doesn’t matter, because Americans tend to be uncomfortable with silence during a conversation. They would rather talk about the weather or the latest sports scores, for example, than deal with silence.
On the other hand, don’t expect Americans to be knowledgeable about international geography or world affairs, unless those subjects directly involve the United States. Because the United States is not surrounded by other nations, some Americans tend to ignore the rest of the world.

Which of the following statements is NOT true according to the passage

A．Friendships among Americans tend to be casual.

B．Americans do not like to depend on other people.

C．Americans always seem to be on the go.

D．Americans know a lot about international affairs.