问题 实验题

照如图所示那样,在桌面上竖立一块玻璃板,把一点燃的蜡烛放在玻璃板前面,可以看到玻璃板面出现蜡烛的像.

(1)要研究玻璃板成像的特点,问键的问题是设法确定像的位置。仔细想想,实验时具体的做法是_________,我们这样确定像的位置,凭借的是视觉效果的相同,因而可以说是采用了_________的科学研究方法.

(2)某同学在实际实验中测量如下数据,并记录在下表中.

实验次数点燃蜡烛到镜面距离(cm)点燃蜡烛的高度(cm)镜后蜡烛到镜面距离(cm)镜后蜡烛应有高度(cm)
110121012
214101410
3188188
由表中数据可得到的结论有:①_____________________.②_____________________.

答案

(1)在像的位置上放一个相同的蜡烛;等效替换 

(2)①像与物体的大小相同 ②像与物体到镜面距离相等

(1)取两只蜡烛,一只点燃在玻璃板前,一只不点燃,在玻璃板后,使后面的蜡烛与前面蜡烛的像完全重合,后面蜡烛的位置就是前面蜡烛的像的位置,这是一种等效替代的方法.

(2)由表中物距和像距的数值相等可得出:像到平面镜的距离等于物体到平面镜的距离.像与物体等大.

故答案为:(1)在像的位置上放一个相同的蜡烛;等效替换 (2)①像与物体的大小相同 ②像与物体到镜面距离相等

阅读理解

阅读理解

阅读下面短文,从每题所给的A、B、C、D 四个选项中选出最佳选项。

     Cindy, Jerry and Mary are giving their opinions about a good friend.  

Cindy: I think a good friend should be honest(诚实的). That's more important than any other things

and is where a good friendship starts. If a friend isn't honest, he may lose his friends' trust.

Jerry: I think a good friend has to be generous. Here "generous" doesn't mean he has to give  his

friends his lunch money or his clothes. It means he should share(分享) his ideas and feelings with

his friends. In fact, his friends can know him better in this way.

Mary: In my opinion, a good friend should understand his friends. When there's  something

wrong between him and his friends, he must put himself in his friends' place and  think more for his

friends.

1. What does the underlined sentence(句子) mean?

A. To be honest is the most important.  

B. To be honest is as important as other things.

C. To be honest is not so important.    

D. Honest people g et more things than others

2. Jerry would like to make friends with people who ______.

A. give him lunch money

B. know him very well

C. tell him their ideas and feelings

D. give him some clothes

3. Mary thinks friends should ______.

A. visit each other often

B. go to more places to play

C. understand each other

D. help each other do more things

4. Which of the following is NOT true?

A. These three people are talking about what they think a good friend should be.

B. Cindy thinks to be honest is the base(基础) of a good friendship.

C. Mary would like to make friends with people who think more for friends.

D. A man is generous. That means he is very clever.

5. What does the underlined word "trust" mean in Chinese?

A. 夸奖        

B. 批评    

C. 理解        

D. 信任

选择题