问题 实验题

在测定“小灯泡的电功率”的实验中,已知电源电压为6V,小灯泡的额定电压为2.5V,小灯泡的电阻约为10Ω,滑动变阻器上标有“20Ω  IA”字样.图15是小向同学没有连接完的实物电路。

(1)请你用笔画线代替导线,将实物电路连接完整;

(2)实验中,小向同学连接好电路后,闭合开关,移动滑片,发现小灯泡始终不亮,且电压表有示数,电流表无示数,则故障的原因可能是_______________________;

(3)故障排除后,闭合开关,移动滑动变阻器的滑片到某一点,电压表的示数如图16甲所示,电压是 _________V,要测量小灯泡的额定功率,应将滑片P向__________端滑动(选填“A”或“B”);

(4)当小灯泡正常发光时,电流表的示数如图16乙所示,则小灯泡的额定功率是_____W。小灯泡正常发光时灯丝的电阻是______Ω

答案

(1)说明:电流表必须用0.6A的量程

(2)小灯泡断路    

(3)2.2;滑动变阻器若接A填A,若接B填B

(4)0.6;10.4

实验中,小向同学连接好电路后,闭合开关,移动滑片,发现小灯泡始终不亮,且电压表有示数,电流表无示数,则故障的原因可能是小灯泡断路;故障排除后,闭合开关,移动滑动变阻器的滑片到某一点,电压是2.2V,要测量小灯泡的额定功率,应将滑片P向右端滑动。

完形填空

For each blank in the following passage there are four words or phrases marked A, B, C and D. Fill in each blank with the word or phrase that best fits the context.

Until I took Dr. Offutt’s class, I was an underachieving student. But I left that class

50 _never to underachieve again. He not only taught me to think, he convinced me, as much by examples as words, that it was my  _51   obligation to do so and to serve others.

Neither of us could know how our relationship would   52   over the years. When I first came back to DeMatha to teach English, I worked for Dr. Offutt, the department chair. My discussions with him as he mentored me were like graduate seminars in adolescent (青少年)  53    , classroom management and school leadership.

After several years, I was   54     department chair, and our relationship shifted again. I thought that it might be  55   to chair the department, since all of my former English teachers were  56  there, but Dr. Offutt supported me  57    . He knew when to give me advice about curriculum, texts and personnel, and when to let me  58   my own course.

In 1997, I needed his  59 about leaving DeMatha to become principal at another school.  60     he had asked me to stay at DeMatha, I might have.   61    , he encouraged me to seize the new opportunity.

Five years ago, I became the principal of DeMatha.   62     , Dr. Offutt was there for me, letting me know that I could   63    him as I tried to fill such big shoes. I’ve learned from him that great teachers have an inexhaustible wealth of lessons to teach. Even if his students don’t know it yet, I know how   64   they are: I’m still one of them.

50. A. anxious             B. eager                  C. determined         D. worried

51. A. family              B. legal          C. academic           D. moral

52. A. evolve              B. stay          C. remain              D. worsen

53. A. process            B. procedure     C. development        D. movement

54. A. called               B. appointed      C. entitled           D. offered

55. A. awkward           B. uneasy         C. unnatural          D. insensitive

56. A. once               B. already        C. still               D. never

57. A. through            B. throughout     C. at the beginning      D. in the end

58. A. chart             B. head           C. describe           D. manage

59. A. opinion            B. request         C. permission         D. promise

60. A. Even if             B. Although        C. If                  D. When

61. A. Naturally           B. Instead        C. Consequently        D. Peacefully

62. A. Once again         B. Now and then  C. Hopefully                       D. Surprisingly

63. A. count on           B. account for      C. call on              D. appeal to

64. A. earnest           B. worried         C. fortunate           D. desperate

多项选择题