问题 实验题

小强要测一个定值电阻的阻值:

(1)当要闭合开关时,小强发现如图(1)所示电路还没有连接完整,请你用笔画线代替导线,将电路连接完整;并将此时的电路图画在方框(2)中。

(2)连接完电路,闭合开关,小强发现,电流表无示数,而电压表示数接近3V,则出现故障的原因可能是:                            

(3)排除故障后,调节滑动变阻器,电流表的示数电压表的示数如图3所示,由此求出待测电阻为    Ω.

至此,小强说已经完成实验,同组的小聪认为不妥,因为                          

(4)另一组的小玥同学用如下图所示的电路测未知电阻RX的阻值,并将数据记录在表中,则该未知电阻RX的阻值为     Ω,该电路的电源电压为     V。

答案

(1)如图所示 (2)电阻R断路     (3)10 没有多次测量求平均值减小误差

(4)10   6 

题目分析:小强要测一个定值电阻的阻值,连接完电路,闭合开关,小强发现,电流表无示数,而电压表示数接近3V,则出现故障的原因可能是和电压表并联的电阻R断路。排除故障后,调节滑动变阻器,电流表的示数电压表的示数如图3所示,电压表的示数是2.4V,电流表的示数是0.24A,由此求出待测电阻为10Ω.这个实验的不妥之处是没有多次测量求平均值减小误差。另一组的小玥同学用如图4所示的电路测未知电阻Rx的阻值,电压表并联在滑动变阻器的两端,根据数据列出等式0.1Rx+5V="0.2" Rx +4V,解得Rx=10Ω,电源电压是U=0.1A×10Ω+5V=6V。

完形填空

If you are worried about things and are under a lot of stress at work or school, then you are probably not sleeping well. Worry can keep you awake, tossing(翻来覆去) and turning in bed until the early hours of the morning when you eventually fall asleep. When you wake up, you don’t feel refreshed, but tired and worn out and unable to face a new day.

Dr. Henry Winkle, in a recent newspaper article entitled Stress and Sleep, indicates that        . Dr. Winkle says, “The more we worry, the less we sleep, the more we are unable to deal with stress. If we can find a way to get a good night’s sleep,” he adds, “we can often find the energy to deal with what’s worrying us.”

So, what is a good night’s sleep? Research shows that the amount of sleep which people need in order to keep healthy varies a lot. Seven hours is about average amount, though strangely enough, sleeping longer often gives you a headache instead of making you feel more refreshed.

Dr. Winkle believes that preparing for sleeping is important. People who work late should try to give themselves a short break and do something restful before going to bed. This could be watching TV or listening to music. Doing some exercise earlier in the day should help you to feel physically as well as mentally tired. A bedtime drink can also help, but coffee or tea should be avoided as they contain caffeine and will keep you awake. “When you put the light out,” Dr. Winkle says, “concentrate on relaxing your muscles, working slowly up from your feet, and you’ll be asleep before you know it.”

小题1:What is the best title of the passage? (Please answer within 5 words)

                                                                                    

小题2:Which sentence in the passage can be replaced by the following one?

People shouldn’t go to sleep immediately but should take a break after working late in the night.

                                                                                    

                                                                                    

小题3:Please fill in the blank in the second paragraph with proper words or phrases to complete the sentence. (Please answer within 10 words)

                                                                                    

小题4:Someone says that the longer you sleep, the better you feel. Try to find an argument from the passage against the idea. (Please answer within 15 words)

                                                                                    

小题5:Translate the underlined sentence in the first paragraph into Chinese.

                                                                                        

单项选择题