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1、一、光的干涉现象一、光的干涉现象-杨氏干涉实验杨氏干涉实验二、运用光的波动理论进行分析二、运用光的波动理论进行分析三、干涉条纹的间距与哪些因素有关三、干涉条纹的间距与哪些因素有关四、波长和频率四、波长和频率一、光的干涉现象、光的干涉现象-杨氏干涉实验杨氏干涉实验1、装置特点、装置特点：（1）双缝很近 0.1mm，（2）双缝S1、S2与单缝S的距离相等，单缝 双缝红滤色片S1SS2屏幕2、要用单色光要用单色光 单单孔孔的的作作用用：是是获获得点光源得点光源 双双孔孔的的作作用用：相相当当于于两两个个振振动动情情况况完完全全相相同同的的光光源源，双双孔孔的的作用是获得相干光源作用是获得相干光源下一
2、步 3、实验的改进：、实验的改进：指出用狭缝代替小孔，可以得到同样清晰，但明亮得多的干涉条纹。用氦氖激光器发出的激光演示双缝干涉实验。4、实验演示、实验演示 5、干涉图样的特点、干涉图样的特点：（1）形成明暗相间的条纹 （2）亮纹间等距、暗纹间等距 （3）两缝S1、S2中垂线与屏幕相交位置是亮 条纹-中央亮纹提出问题提出问题：（1）为什么会出现这样的图象？（2）怎样用波动理论进行解释？复习：（1）两列波在波峰和波峰相遇或波谷与波谷相遇时振幅变大，说明此点为振动加强点。（2）两列波在波峰和波谷相遇时振幅变小，说明此点为振动减弱点。二、运用光的波动理论进行分析二、运用光的波动理论进行分析（3）对光
3、发生干涉时 若光互相加强，出现亮条纹 若光互相削弱，出现暗条纹 红滤色片单缝 双缝S1SS2屏幕 由于从由于从S1S2发出的光是振动情况完全相发出的光是振动情况完全相同，又经过相同的路程到达同，又经过相同的路程到达P点，其中一条点，其中一条光传来的是波峰，另一条传来的也一定是波光传来的是波峰，另一条传来的也一定是波峰，其中一条光传来的是波谷，另一条传来峰，其中一条光传来的是波谷，另一条传来的也一定是波谷，确信在的也一定是波谷，确信在P点激起的振动总点激起的振动总是波峰与波峰相遇或波谷与波谷相遇，振幅是波峰与波峰相遇或波谷与波谷相遇，振幅AA1+A2为最大，为最大，P点总是振动加强的地方，点总是
4、振动加强的地方，故应出现亮纹，这一条亮纹叫中央亮纹。故应出现亮纹，这一条亮纹叫中央亮纹。S1S2P=0P中央亮纹双缝S1S2屏幕P1 第一亮纹双缝S1S2屏幕S1S2P1 取P点上方的点P1，从S1S2发出的光到P1点的光程差就不同，若这个光程差正好等于波长的整数倍，比如=S1S2=，出现第一条亮纹。=P2 第二亮纹双缝S1S2屏幕 屏上屏上P1点的上方还可以找到点的上方还可以找到=S1S22的的P2点出现第二条亮纹。点出现第二条亮纹。2P3 第三亮纹双缝S1S2屏幕3 屏屏上上P1点点的的上上方方还还可可以以找找到到=S1S24的的P2点点，=S1S25的的P3点点等等处处的的第第四四条条、
5、第第五五条条亮亮纹纹；在在中中央央明明纹纹P的的下下方方可可找找到到=S1S2的的P1/点点，=S1S22的的P2/点点，=S1S23的的P3/点点等等处处与与中中央央明明纹纹为为对对称称的的第第一一、第第二二、第第三三，第，第n条亮纹。条亮纹。双缝S1S2屏幕P1 第一亮纹 =P 中央亮纹 =0P2 第二亮纹 =2P3/第三亮纹 =3P3 第三亮纹 =3P3/第二亮纹 =2P3/第一亮纹 =Q1 第一暗纹双缝S1S2屏幕S1S2P1/2/2P 中央亮纹 取取P点上方的点点上方的点Q1，与两个狭缝，与两个狭缝S1、S2路程差路程差=S1S2/2，其中一条光传，其中一条光传来的是波峰，另一条传来
6、的就是波谷，来的是波峰，另一条传来的就是波谷，其中一条光传来的是波谷，另一条传来其中一条光传来的是波谷，另一条传来的一定是波峰，的一定是波峰，Q1点激起的振动总是波点激起的振动总是波峰与波谷相遇，振幅最小，峰与波谷相遇，振幅最小，Q1点总是振点总是振动减弱的地方，故应出现暗纹。动减弱的地方，故应出现暗纹。Q2 第二暗纹双缝S1S2屏幕 屏上屏上Q1点的上方点的上方还可以找到还可以找到=S1S23/2的的Q2点出点出现第二条暗纹。同现第二条暗纹。同样可以找到第三条样可以找到第三条暗纹暗纹Q3，在中，在中央明纹下方也可以央明纹下方也可以找到对称的找到对称的Q1/、Q2/、Q3/等暗纹。等暗纹。3/
7、2Q1 第一暗纹P 中央亮纹双缝S1S2屏幕P1 第一亮纹 =P 中央亮纹 =0P2 第二亮纹 =2P3/第三亮纹 =3P3 第三亮纹 =3P3/第二亮纹 =2P3/第一亮纹 =Q2 第二暗纹Q 1 第一暗纹Q3 第三暗纹Q3/第三暗纹Q2/第二暗纹Q1/第一暗纹=5/2=/2=3/2=5/2=3/2=/2（1 1）空间的某点距离光源空间的某点距离光源S1S1和和S2S2的路程的路程差为差为0 0、1 1、2 2、3 3、等、等波长的整波长的整数倍（半波长的奇数倍）数倍（半波长的奇数倍）时，该点为振动时，该点为振动加强点。加强点。总结规律总结规律光程差光程差 =k=k（k=0k=0，1 1，2
8、 2，等），等）亮纹亮纹 （2 2）空间的某点距离光源）空间的某点距离光源S1S1和和S2S2的路程差为的路程差为/2/2、3/23/2、5/25/2、等等半波长的奇数倍半波长的奇数倍时，该点为振动时，该点为振动减弱点。减弱点。光程差光程差 =（2k-1)/2(k=1,2,3,2k-1)/2(k=1,2,3,等）等）暗纹暗纹表达式表达式：亮纹：光程差亮纹：光程差 =k（k=0，1，2，等），等）暗纹：光程差暗纹：光程差 =（2k-1)/2 (k=1,2,3,等）等）结论结论：双缝S1S2屏幕三、干涉条纹的间距与哪些因素有关三、干涉条纹的间距与哪些因素有关?xx条纹间距的含义：亮纹或暗纹之间的距
9、条纹间距的含义：亮纹或暗纹之间的距离总是相等的，亮纹和亮纹之间的距离或离总是相等的，亮纹和亮纹之间的距离或暗纹和暗纹之间的距离叫做条纹间距。暗纹和暗纹之间的距离叫做条纹间距。我们所说的亮纹是指最亮的地方，我们所说的亮纹是指最亮的地方，暗纹是最暗的地方，从最亮到最暗有一个暗纹是最暗的地方，从最亮到最暗有一个过渡，条纹间距实际上是最亮和最亮或最过渡，条纹间距实际上是最亮和最亮或最暗和最暗之间的距离。暗和最暗之间的距离。1 1、什么是干涉条纹的间距、什么是干涉条纹的间距?双缝S1S2屏幕三、干涉条纹的间距与哪些因素有关三、干涉条纹的间距与哪些因素有关?Ld 重做干涉实验，并定性寻找规律重做干涉实验，
10、并定性寻找规律 d d、不变，只改变屏与缝之间的不变，只改变屏与缝之间的距离距离L LL L越大，条纹间距越大越大，条纹间距越大 L L、不变，只改变双缝距离不变，只改变双缝距离d dd d越小，条纹间距越大越小，条纹间距越大2 2、干涉条纹的间距与哪些因素有关、干涉条纹的间距与哪些因素有关?三、干涉条纹的间距与哪些因素有关三、干涉条纹的间距与哪些因素有关?L、d不变，用不同的单色光进行实验 红光的条纹间距最大，紫光的最小。3、亮（暗）纹间距的公式、亮（暗）纹间距的公式推导推导x=在狭缝间的距离、狭缝与屏的距离都不变的条件下，用不同颜色的光做实验，条纹间的距离是不同的。红光的条纹间距最大，紫光
11、的条纹间距最小。1、红光的波长最长，紫光的波长最短。、红光的波长最长，紫光的波长最短。四、波长、频率和光速四、波长、频率和光速 红光的波长最长，紫光的波长最短。红光的波长最长，紫光的波长最短。x=波长和频率的乘积等于波速，不同色的光在真空中的传播速度相同。所以：波长越长频率越小，波长越短频率越大。2、任何单色光在真空中的传播速度相同，但它、任何单色光在真空中的传播速度相同，但它们的波长不同。波长、频率和光速的关系为。们的波长不同。波长、频率和光速的关系为。公式：3、光的颜色由频率决定、光的颜色由频率决定 光由一种介质进入另一种介质中频率不变光的颜色波长(m)频率 f(1014Hz)光的颜色波长
12、(m)频率 f(1014Hz)红0.770.623.94.8绿0.580.495.26.1橙0.620.64.85.0蓝靛0.490.456.16.7黄0.60.585.05.2紫0.450.406.77.54、各色光在真空中的波长和频率的范围见下表：、各色光在真空中的波长和频率的范围见下表：一束红光从空气进入玻璃，一束红光从空气进入玻璃，、v、如何变化？如何变化？同一色光在不同的介质中的传播时速度不同，但频率不变，因频率由光源决定，与介质无关。白光的干涉图样是什么样？白光的干涉图样是什么样？明暗相间的彩色条纹；中央为白色亮条纹；干涉条纹是以中央亮纹为对称点排列的；在每条彩色亮纹中红光总是在外
13、缘，紫光在内线。【学生实验】观察白炽灯光的干涉。一、光的干涉现象一、光的干涉现象-杨氏干涉实验杨氏干涉实验二、运用光的波动理论进行分析二、运用光的波动理论进行分析三、干涉条纹的间距与哪些因素有关三、干涉条纹的间距与哪些因素有关四、波长和频率四、波长和频率例例1 声波和光波都从空气进入水中，则（声波和光波都从空气进入水中，则（）A它们波速都变小，频率都不变，波长都它们波速都变小，频率都不变，波长都要变小要变小B它们它们 的波速都变大，频率都不变，波长的波速都变大，频率都不变，波长都变大都变大C声波波速变大，波长变大，光波波速变声波波速变大，波长变大，光波波速变小，波长变小小，波长变小D声波波速不
14、变，波长不变，光波波速变声波波速不变，波长不变，光波波速变小，频率变小小，频率变小例2 在双缝干涉实验中，入射光的频率为5 ，从双缝射出的到达屏上的某点的路程差为1500 ，那么该点将出现什么样的条纹？3 3薄膜干涉薄膜干涉 （1）薄膜干涉的成因当 =（n ）时为亮纹，当 =（2n+1）/2时为暗纹（2）薄膜干涉的应用A用干涉法检查平面B增透膜例3 如图示的是用单色光干涉法检查某块厚玻璃板b的上表面是否平整的装置，a为标准样板，检查中所观察到的干涉条纹是由下列哪两个表面反射的光线叠加而成的？Aa的上表面和b的下表面Ba的上表面和b的上表面Ca的下表面和b的上表面Da的下表面和b的下表面ab单色
15、光标准样板薄片厚玻璃板如图所示，用单色光照射透明标准板M来检查被检查体N的上表面的平直情况，观察到的现象如图所示条纹中的P和Q的情况，这说明（）A N的上表面A处向上凸起B N的上表面B处向上凸起C N的上表面A处向下凹陷D N的上表面B处向下凹陷ABMNpyramid 金字塔Stonehenge 巨石阵wheel 车轮golden sunlight.金色阳光Tiananmen Square 天安门广场army 军队Jay Chou 周杰伦Jay Chou is handsome.He is my favourite actor.arrow 箭bow 弓 The Trojan War the
16、Trojan War told in HomersIliad and Odyssey 荷马伊利亚特奥德赛 the prince of Troy fell in love with Helen,the queen of Sparta.斯巴达 He kidnapped her and took her to Troy.All the Greek went to bring her back.绑架 the war lasted for ten years.The night of the horseLook at the title,the picture and the last paragrap
17、h,and then answer the two questions.It was a huge wooden horse.1.What kind of horse it is?2.How did the Greeks win the war?They won the war with a trick.Read through the whole passage and match the main idea for each part.P1-2P3-6P7P8-9The Trojans celebrate their victory and then go to sleep.The Gre
18、ek soldiers inside the horse open the city gates and let in the Greek army.The Greek army capture Troy.A Trojan soldier announces that the Greek army has left and his captainConfirms it.The soldier found a huge,wooden horse outside their city,and the captainorders it to be moved into the city.1.How
19、was the soldier probably feeling when he came down the stairs,surprised or peaceful?2.What did the captain think when he saw the empty plain?3.What did the captain think about the horse?4.What did the citizens of Troy do that night?5.Where did the six Greek soldiers hide?6.Did the horse have somethi
20、ng to do with the trick?How?Read the passage and then answer the following questions1.How was the soldier probably feeling when he came down the stairs,surprised or peaceful?2.What did the captain think when he saw the empty plain?3.What did the captain think about the horse?Read the passage and the
21、n answer the following questionsHe probably was feeling surprised.The captain thought that they had won the war.He thought it was too big for the Greeks to take.4.What did the citizens of Troy do that night?5.Where did the six Greek soldiers hide?6.Did the horse have something to do with the trick?H
22、ow?They celebrated their success.They hid in the horse.Yes.(answers vary.)Part B Look and think These pictures show some of the events in the story on Page 58.Arrange them in the correct order.Answers:c d b a f e Summary The war between the Troy and the Greeks lasted ten years.At last,the Greeks won
23、 the war with a t_.They pretended to leave the city of Troy,but they left a huge w_ horse behind.The Troy thought they have w_ the war so they c_,making j_ about the Greeks.They were so happy about their win that all of them went to sleep,i_ the gate guard.The Greek soldiers i_ the wooden horse open
24、ed the gate and let their army in.In this way,they c_ the Troy city.rickoodenonelebratedokesncludingnsideaptured1.大木马2.举行一次比赛3.冲下台阶4.一会儿后5.朝下看6.再多等一小时7.进入城里8.拿走，带走9.除之外10.拖进城11.开玩笑12.成功做成某事13.用计谋a huge wooden horsehave hold run a competitionrush down the stairsseconds laterlook down atwait for anoth
25、er hour=wait for one more hourenter the city=get into city take awayexcept forpull/drag into the citymake jokes about=laugh at=make fun ofsucceed in doing sth.with a trick Useful expressions1.A newspaper ran a short competition on famous tales from pete(v)比赛比赛-competition competitor competitive(n.)比
26、赛(n.)比赛者(adj.)比赛的2.Seconds later,the captain stood on the high wall of the city of Troy,and looked down at the empty plain.(1)seconds later=after a while 一会儿后一会儿后(几秒钟后几秒钟后)(2)the city of Troy 特洛伊城特洛伊城 the city of Shenzhen=Shenzhen city (3)look out=be careful look for 寻找寻找 look after 照顾照顾 look over=e
27、xamine look down upon sb 看不起某人看不起某人 look up to 看得起，尊重看得起，尊重 3.It was too big for them to take with them.=It was so big that they couldnt take it with them.take bring carry随身携带4.They all went to sleep,including the gate guards.The band played many songs,including some of my favorite.十个人出席了会议，包括我爸爸。十个
28、人出席了会议，包括我爸爸。Ten members are present at the meeting,including my father.5.By midnight,the square was empty,except for the giant horse.except for:not including 除除 之外（不包括）之外（不包括）Except for one old lady,the bus was empty.比较：比较：We go to school every day except Saturday and Sunday.We have winter holiday
29、besides summer holiday.6.The six Greek soldiers in the wooden horse waited for another hour,to be sure.We need another ten students =We need ten more students.Paraphrase 1.The Greeks tried to capture our city.2.The square was empty,except for the giant horse.3.They succeeded in capturing it with a t
30、rick.The Greeks tried to take over our city.There was nobody but the giant horse in the square.There was only a giant horse in the square.They managed to capture it with a trick.They captured it successfully with a trick.1 d-2 h-3 a-4 e-5 b-6 g-7 c-8 fTroySpartaGods and GoddessesKing of TroyKing Men
31、elausKing of the GodsZeusPrince ParisQueenHelenGoddess of loveAphroditeHow did the Trojan War start?1 d-2 h-3 a-4 e-5 b-6 g-7 c-8 fTranslate the following sentences1.我已经写了几个电脑游戏。2.我经营这家公司两年了。3.你把你的书整理好了吗？4.我还没有把衣服挂起来。5.他铺床铺了吗？I have already written several computer games.I have run the business for
32、two years.Have you organized your books?I havent hung up the clothes.Has he made the bed?现在完成时结构：现在完成时结构：have/has+动词过去分词动词过去分词一一.动词的过去分词形式动词的过去分词形式1.规则动词规则动词finish-finished-finishedlive-lived-livedcarry-carried-carriedstopstopped-stoppedfailorganizeachieveempty-failedfailed -organized-organized -ach
33、ieved achieved -emptied emptied2.不规则动词gowentgonesee-sawseenforgetspendsweephang forgot forgotten spent spent-swept-swept-hung-hung (1).for+表示一段时间的短语 (2).since+表示过去时间点的词语 (3).since+表示过去时间的时间状语从句eg.I have been a teacher _ a year.He has been at this school _ 1992.We have learned 1,000 English words _ w
34、e came to this school.forsincesince already,yet;never,ever;just,before 有此类副词时,常强调动作完成.eg.Have you _been to Japan?I have _ finished my homework.I have _ finished my homework.I havent finished my homework _.everjustalreadyyet二.现在完成时句中常见的时间词1.Weve already finished the work.I havent swept the floor yet.
35、Have you emptied the rubbish bin yet?already 已经用于肯定句 yet 还用于疑问句和否定句2.She has never heard of it,has she?Have you ever been to England?never从未没做过 ever曾经做过3.Ive just written several computer games.I have watched this film before.just 刚刚 before 以前 用 since,for或者ago填空1.Jill has been in Ireland _ Monday.si
36、nce2.Jill has been in Ireland _ three days.for3.My aunt has lived in Australia _ 15 years.for4.Margaret is in her office.She has been there _ 7 oclock.since5.Mike has been in hospital _ October.since6.They got married six months _.ago7.I first met Sue two years _.ago三.区分短暂性动词与持续性动词.表示短暂性(瞬间性)的动词在现在完
37、成时的句中不能和一段时间连用.即for,since短语或how long问句1.I came here two years ago.I have been here for two years.I have been here since two years ago.2.I joined the army 5years ago.I have been a soldier for 5 e/arrivego out leavebeginbuyborrowjoindiecatch a coldbe at/in be outbe away(from)be onhavekeepbe a member o
38、fbe deadhave a cold瞬间动词和延续性动词转换练习：1.I bought the book two days ago.I have had the book for two days.2.He borrowed the book three months ago.He has kept the book since 3 months ago.3.I got to know Jane 2 years ago.I have known Jane for 2 years.4.I joined the League three years ago.I have been a Leagu
39、e member for 3 years.5.Ken joined the army two years ago.Ken has _ _ _ for two years.Ken has _ _ the army for two years.been a soldierbeen in6.He left his hometown 10 years ago.He has _ _ _ his hometown since 10 years ago/for 10years.been away from7.The film began 10 minutes ago.The film has _ _ for
40、 10 minutes.been on8.I got a cold two days ago.I have _ a cold since two days ago.had9.The film finished 5 minutes ago.The film has _ _ for 5 minutes.been over10.The man came here ten minutes ago.The man has _ here for 10 minutes.been11.Linda and Frank married in 1989.They _ since 1989.have been mar
41、ried改错:How long have you become a league member？For more than one year.Have you arrived here since last night.Yes，youre right.The dog has died for a month.He has gone to Shanghai twice.How long have you been at this school?Since two years.beenbeenbeen deadbeen ago.For IV.exercise1.My mother_ the win
42、dows already,so the room looks much brighter.A.has cleaned B.had cleaned C.is cleaning2.The engineer _ shopping with his wife yesterdayA.has gone B.has went C.went3.-Wheres your mother?-She _ the hospital.A.has gone to B.has been to C.has gone in 4.Oh,Mrs.King,your necklace looks nice.Is it new?No,I
43、 _ it for two years.A.had B.have had C.bought D.have bought 5.I havent seen you _ last Friday.A.for B.since C.fromD.on6.His grandfather _ for over two years.A.has died B.has been dead C.has dead D.died Tell your friends about the Troy war in your words.(more than 80 words)Read the passage again and then correct the wrong statements1.The captain was sad to see the empty plain.2.The horse was on wheels.3.The Trojans pushed the horse into the city.4.The gate guard went to sleep,too.5.The gate guard opened the main gates.6.The Troy lost the war.happydraggedGreek soldiers Bye-bye!