问题 问答题

(1)小明利用光具座、凸透镜、蜡烛、火柴、光屏,做“探究凸透镜成像规律”的实验.

①光具座上有A、B、C三个滑块用于放置凸透镜、光屏或蜡烛(如图1甲所示),其中在B上应放置:______.

②实验中发现光屏上成像如图1乙所示,你认为造成这种现象的原因是:______.

③小明在实验过程中,保持凸透镜位置不变(如图2所示),分别按以下情况调整好光屏的位置:

在给定的A、B、C、D、E、F、G各点中,把烛焰放在______点光屏上出现清晰倒立缩小的实像且最小;把烛焰放在______光屏上出现清晰倒立放大的实像且最大.

④实验室给小明提供了焦距分别为10cm、40cm两种凸透镜,要想顺利完成探究实验,小明必须选择焦距为______cm的凸透镜.

(2)常用体温表的刻度部分为三棱体,横截面积如图3所示.我们在测量体温时,分别沿A、B、C、D方向观察读数.其中沿______方向观察易于读数,这是因为体温计在设计时应用了

______原理.

答案

(1)①在做“探究凸透镜成像规律”实验时,要将蜡烛、凸透镜、光屏从左到右依次放在光具座上,所以中间B位置一定放置凸透镜.

故答案为:凸透镜.

②根据图可知,像在光屏的上方,原因是没按实验要求,焰心、凸透镜的光心及光屏的中心在同一高度上,为了把像成在光屏的中央,可以将蜡烛向上移动或透镜向下移动或光屏向上移动.

故答案为:凸透镜光心、蜡烛焰心、光屏中心不在同一高度.

③由图可知,A、B两点均在2倍焦距以外,由凸透镜成像规律可知,都成倒立缩小实像,但A点距离透镜的距离大于B点,所以A点成的像最小;

由图可知,D、E两点均在1倍焦距和2倍焦距之间,由凸透镜成像规律可知,都成倒立放大的实像,但E点距离透镜的距离小于D点,所以E点成的像最大.

故答案为:A;E.

④:如果选择焦距是40cm的透镜,当“研究凸透镜成像的规律”中的u>2f时,即物距大于80cm,此时f<v<2f,即像距大于40cm小于80cm,而实验所用的光具座上标尺的刻度范围是“0~100cm”,所成的像位置超出了光具座的范围,在光屏上不能看到清晰的像.所以不能选焦距是40cm的透镜,只能选择焦距是10cm的透镜.

故答案为:10.

(2)常用体温计的刻度部分为三棱镜,横截面如图3所示,其正面B处成圆弧状,这时圆弧形玻璃的作用相当于凸透镜,物体放在小于焦距处,它能够成一个正立、放大的虚像,这样就可以看清体温计内极细的水银柱,以便于读数.

故答案为:B;物体放在小于焦距处,凸透镜成放大正立虚像.

阅读理解

阅读理解。

     It is said that all dreams serve a purpose (目的). While there is no agreement among scientists about

why we dream, there are many ideas about the different kinds of dreams we have.

    One common kind of dream is the repeating dream, in which the same story is repeated again and again,

often for many months or even years. Some believe these are a sign people have a problem in their life and

once that problem is gone then the dream will stop. Others think they are a way to help people remember

something very important.

    Another well-known kind of dream is the nightmare. The pictures and stories in such dreams make

people very afraid and dreamers usually remember them far more clearly than normal dreams. The cause

of such dreams may be seeing something terrifying such as a car accident or some deadly snakes. Others

think such dreams may be trying to make a person pay attention to something that is dangerous in their life.

    Daydreams happen during wake-time when we forget where we are or what we are doing and find

ourselves in a made-up story or unreal world." We often daydream when we are doing something that is

not interesting or exciting. They help us think about our future.

    Lucid dreams are the most fun. These happen when dreamers suddenly understand that they are dreaming.

Instead of waking up, they stay in the dream and are able to control what happens in the dream as if they are

making a movie.

1. The underlined word "they" (in paragraph 2) refers to "______".

A. dreams

B. problems

C. dreamers

D. scientists

2. The underlined word "terrifying" (in paragraph 3) is closest in meaning to ______.

A. frightening

B. interesting

C. disappointing

D. amazing

3. When might a person daydream?

A. During a very interesting movie.

B. While playing at a fun park.

C. While listening to an uninteresting talk.

D. When making a movie.

4. How do we know if We are lucid dreaming?

A. We can remember the dream very clearly.

B. We can control what happens in the dream.

C. We think that the dream is like a movie.

D. We feel very nervous after we wake up.

5. What is the best title of the passage?

A. Daydreaming of You

B. Enjoy Your Dream

C. What Dreams Mean

D. Where Dreams Go

读图填空题

东海原甲藻(简称甲藻)是我国东海引发赤潮的藻种之一,研究甲藻光合作用的生理特性可为认识赤潮发生机理提供重要信息。

  某研究小组探究pH对甲藻光合作用的影响,设计了以下实验:将生长旺盛的甲藻等量分成5组培养,各组藻液pH分别设定为6.0、7.0、8.0、9.0、10.0,在黑暗中放置12h,然后在适宜光照等相同条件下培养,随即多次测定各组氧气释放量并计算净光合速率。将实验结果绘制成下图。

(1)本实验除了通过测定氧气释放量,还可以通过测定_______吸收量来计算净光合速率。

(2)黑暗放置过程中,藻液pH会有所变化,因此在测定氧气释放量前,需多次将各组pH分别调到______,这是控制实验的_________变量。

(3)若甲藻长时间处于pH10.0条件下,甲藻_____(能、不能)正常生长繁殖,请据图分析并说明原因:_________________________。

(4)实验表明,甲藻光合作用适宜pH6.0~9.0。但海水在该pH条件下,一般不会发生赤潮,原因是发生赤潮除了与pH、温度、光照强度等因素有关外,最主要还与海水的_________有关。

(5)研究小组进一步探究了温度对甲藻光合作用的影响。根据实验结果得出:甲藻生长繁殖的适宜温度为15℃-30℃,最适温度为25℃左右,当温度为9℃和33℃时,甲藻不能正常生长繁殖。请根据这些信息在下图中画出净光合速率随温度变化的示意曲线。