问题 实验题

如图所示是“研究电磁感应现象”的实验装置。

小题1:将图中所缺导线补接完整。

小题2:如果在闭合开关时发现灵敏电流计的指针向右偏了一下,那么合上开关后,将原线圈迅速从副线圈拔出时,电流计指针将____???_______;原线圈插入副线圈后,将滑动变阻器滑片迅速向右移动时,电流计指针将___???__________。(以上两空选填“向右偏”、“向左偏”或“不偏转”)

答案

小题1:

小题2:

此题涉及电学实验研究电磁感应现象,探讨电磁感应现象产生的条件。由电源电键滑动变阻器和小螺线管组成闭合回路,控制磁场的变化。由大螺线管和电流计组成闭合回路,探究电磁感应现象。当在闭合开关时发现灵敏电流计的指针向右偏了一下,此时螺线管中B中磁通量变大。将原线圈迅速从副线圈拔出时,磁场方向与刚才相同,但是磁通量减小,感应电流与刚才的感应电流方向相反,即电流计指针将向左偏;原线圈插入副线圈后,将滑动变阻器滑片迅速向右移动时,电阻变小,电流变大,磁通量变化与闭合电键时相同,电流计指针将向右偏。本题考查电磁感应现象的条件,同时涉及到了楞次定律的应用,难度一般。

阅读理解

阅读理解。

     About six years ago I was eating lunch in a restaurant in New York City when a woman and a young boy

sat down at the next table. I couldn't help overhearing parts of their conversation. At one point the woman

asked, " So, how have you been?" And the boy, who could not have been more than seven or eight years old,

replied, "Frankly, I've been a little depressed lately."

     This incident stuck in my mind because it confirmed my growing belief that children are changing. As far

as I can remember, my friends and I didn't find out we were "depressed" until we were in high school.

     The evidence of a change in children has increased steadily in recent years. Children don't seem childlike

anymore. Children speak more like adults, dress more like adults and behave more like adults than they used

to.

     Whether this is good or bad is difficult to say, but it certainly is different. Childhood as it once was no

longer exists, why?

     Human development is based not only on innate (天生的) biological states, but also on patterns of access

to social knowledge. Movement from one social role (作用) to another usually involves learning the secrets of

the new status. Children have always been taught adult secrets, but slowly and in stages: we tell sixth graders

things we keep hidden from fifth graders.

     In the last 30 years, however, a secret-revelation (揭示) machine has been brought in 98 percent of

American homes. It is called television. Television passes information to all viewers alike, indiscriminately (不

加区分地). Unable to resist the temptation, many children turn their attention from printed texts to the less

challenging, more vivid moving pictures.

     Communication through print, as a matter of fact, allows for a great deal of control over the social

information to which children have access. Reading and writing involve a complex code of symbol that must

be memorized and practiced. Children must read simple books before they can read complex materials.

1. Traditionally, a child is supposed to learn about the adult world ____.

A. through contact with society

B. naturally and by biological instinct (本能)

C. gradually and under guidance

D. through exposure to social information

2. The phenomenon that today's children seem adult like is due to ____.

A. the widespread influence of television

B. the poor arrangement of teaching content

C. the fast pace of human intellectual development

D. the constantly rising standard of living

3. Why is the author in favor of communication through print for children?

A. It enables children to gain more social information.

B. It develops children's interest in reading and writing.

C. It helps children to memorize and practice more.

D. It can control what children are to learn.

4. What does the author think of the change in today's children?

A. He feels amused by their premature (早熟) behavior.

B. He thinks it is a phenomenon worthy of note.

C. He considers it a positive development.

D. He seems to be upset about it.

选择题