如图甲所示电路，电源电压保持不变。闭合开关S，调节滑动变阻器_爱下问搜题

搜题请搜索小程序“爱下问搜题”

问题计算题

如图甲所示电路，电源电压保持不变。闭合开关S，调节滑动变阻器阻值从最大变化到最小，R₁和R₂中的某个电阻其“I－U”关系图线如图乙所示。求：

（1）定值电阻R₁的阻值；

（2）滑动变阻器的滑片在中点时整个电路消耗的电功率；

（3）在图乙中，作出另一个电阻的“I－U”关系图线。

答案

（1）10Ω（2）（3）

题目分析：（1）由图像可知，乙图为R₁的“I －U”图像，当滑片P在最左端时，

R₁= U/I₁=6V/0.6A=10Ω

（2）由图可知，当滑片在最右端时，I₂=0.2A，

R_总= U/I₂=6V/0.2A=30Ω

R₂= R_总－R₁ =30Ω－10Ω=20Ω

I₃= U/（ R₁+1/2 R₂）=6V/（10Ω+10Ω）=0.3A

P=" U" I₃=6V×0.3A=1.8w

（3）另一个电阻R₂的“I－U”关系图线为一条倾斜的线段，两端点坐标分别为（0V 、0.6A）和（4V 、0.2A），因而图像为：

点评：本题考查滑动变阻器的电流和电压的规律以及滑动变阻器的使用，关键是欧姆定律的应用，要明白电路各个用电器的连接情况，还要会看会做“U-I”关系图象

完形填空

完形填空（共20小题；每小题2分，满分40分）
阅读下面短文，掌握其大意，然后从16-35各题所给的四个选项（A、B、C和D）中，选出最佳选项，并在答题卡上将该项涂黑。
It was the afternoon before Christmas. As the newest doctor in our office, I had to work. The only thing that___16___ my day was the Christmas tree in our waiting room and beautiful___17___ sent to me by my lover.
When I was cleaning my office, our nurse came, saying___18___was anxious to speak with me. As I stepped out of the room,I___19__a tired-looking woman with a___20___ in her arms. ___21___, she explained that her husband--a prisoner was my next___22__. She told me she wasn’t ___23__to visit him in prison and that he had never seen his son． Her___24___ for me was to let them sit in the waiting room longer.___25__my schedule wasn’t full, I agreed. Hardly had her husband ___26___ when the woman’s tired face lit up. I kept watching them laugh, cry, and share their child outside. After almost an hour, I called__27____in. He seemed like a gentle and modest man. While working, I ___28___what he possibly could have done to be put into prison. I tried to make him as ___29___ as possible.
　　At the end of the appointment, I ___30___ him a Merry Christmas—a difficult thing to say to a man headed back to ___31___. He smiled and thanked me. He also said he felt ___32___ that he hadn’t been able to give his wife anything for Christmas. On hearing this, I was inspired with a wonderful ___33___.
I’ll never forget the look on both their faces as the prisoner gave his wife the beautiful roses. I’m not sure who experienced the most ___34___—the husband in giving, the wife in receiving, or myself in having the ___35___to share in this special moment.

小题9:A. request B. suggestion B. demand D. order

D．comfortable

C．astonishment

B．opportunity

单项选择题

下面哪些信息技术是对现代企业管理产生过影响的？（）

A.SCM

B.BPR

C.ERP

D.CRM