问题 问答题

如图是“探究平面镜成像特点”的实验装置,小洋点燃玻璃板前的蜡烛A进行实验,得到了如下数据;

实验序号1234
物到玻璃板的距离/cm10.3017.0220.6022.50
像到玻璃板的距离/cm10.3017.1520.6022.50
(1)实验中,在确定蜡烛B和蜡烛A的像是否完全重合时,小洋的观察位置应该是______;

A.在玻璃板前蜡烛A这一侧的不同位置 B.在玻璃板后蜡烛B这一侧的不同位置

(2)小洋在实验中刻度尺的使用以及读数均正确,但是分析表中数据时发现第二组的数据偏差较大,你认为造成这个偏差的原因可能是______;

A.选用的玻璃板太薄 B.蜡烛B与蜡烛A的像没有完全重合

(3)在上述4次实验中随着蜡烛逐渐远离玻璃板,像的大小将______(填“变大”“变小”或“不变”)

答案

(1)造成误差的原因是多方面的,例如:描的点不对应;玻璃太厚,成两个像;没等到像完全重合就测量等,因第二组的数据有较大的偏差,所以造成这个偏差的原因可能是没等到像完全重合就测量;

(2)因为平面镜所成的像是虚像,在玻璃板前蜡烛A这一侧不同的位置观察才能看到蜡烛的像;

(3)因为平面镜所成的像是与物体等大的虚像,所以实验中随着蜡烛逐渐远离玻璃板,像的大小不会改变.

故答案为:(1)A;(2)B;(3)不变.

阅读理解

Are you tired of looking for love in all the usual places? Nowadays, millions of lonely singles are now going online instead.The World Wide Web is quickly becoming the world’s most popular matchmaker.With so many singles online, dozens of dating sites like Yahoo Personals and Match.com are helping singles find that special someone.Around the world, from America to China, love is now very much online.

Singles are flocking to the Internet mainly because their busy lifestyles leave them little time to look for a significant other.Using dating sites is quick and convenient.They can “meet” a lot more people online than they could by hanging out at a club.Besides , many singles say the regular dating scene has just led them from one bad experience to another and are ready to try something else.They also appreciate the first distance of online dating, which allows them to hide themselves until they are ready to meet someone face to face.Dating sites also make it easy to avoid someone you are not interested in.In the real world, however, ignoring someone you don’t like can be awkward.

Despite all the advantages, online dating also presents its own set of problems.People aren’t always who they claim to be in their online profiles.For instance, someone who tells you he is “handsome, successful and single” might turn out to be homely, unemployed and married.Safety is another concern.You are just as likely to find a criminal online as you are Mr or Miss Right.

Even so, supporters of online dating see things in a positive way.In their opinion, singles can safely play the online dating game with a little common sense.Online dating experts recommend following a few safety tips:

Guard your personal information.Never give out your personal information online.This includes your last name, phone number, home address and place of work.

Watch for red flags.Do any of the people you are chatting with make disrespectful comments? Do they try to control you? Do they give false information about themselves? If so, forget them!

Meet in a safe place.When meeting someone in person, choose a public location with other people around.

Following these tips and you might be able to find the person of your dreams.

小题1:According to the passage, many lonely singles don’t appreciate the regular dating scene because it is ___.

A.unpopular   

B.troublesome

C.convenient 

D.forgettable小题2:This passage is mainly about  

A.getting tired of falling in love in a usual way

B.people with false information on the Internet

C.new technology to find love through the Interent

D.web sites such as Yahoo Personals and Match.com小题3:Which of the following is NOT a suitable place for meeting someone you get to know through the Internet for the first time according to the text?

A.At his/her house.     

B.At a museum.

C.At McDonald’s.  

D.At a bookstore.小题4:From this passage ,we can infer that  

A.there are mostly homely and unemployed people online

B.the police had better find criminals online

C.we can find love only through the dating sites

D.following safety tips ensure a safe online dating experience

单项选择题