工作就用美篇工作版","guide_search_desc":"海量模板范文,一键做同款 工作就用美篇工作版","img_beautify_switch":0,"ad_free":0,"text_direction":"1","template":{},"container":{"id":2346795,"user_id":2385561,"container_id":3,"stick_article_id":"","cover_img_url":"","display_name":"浙教版科学七下","description":"","sort":1,"review_state":0,"ip":"","state":0,"create_time":1582472625},"redirect":{"redirect_type":1,"img_url":false,"link_url":"/wap/downloadpage/backpage","button_bg_color":false,"button_desc":false,"redirect_desc":false},"edit_date_str":"更新于 2022-03-17","current_time":1711697513,"font_name":"","rcmd_meipian":0,"hide_article_link":0,"from_wechat":false,"topk_keywords":[{"name":"直线传播","score":0.2312},{"name":"传播","score":0.183302},{"name":"父母","score":0.146722},{"name":"正误","score":0.142261},{"name":"光线","score":0.135137},{"name":"无影灯","score":0.128363},{"name":"成像","score":0.108112},{"name":"中沿","score":0.105607},{"name":"光源","score":0.105438},{"name":"真空","score":0.098387}],"content":{"article_id":212981784,"content":[{"audio_music_id":0,"img_height":390,"img_size":76,"img_url":"https://ss2.meipian.me/users/2385561/4e5237b973fb420d429492bb3a9f774d.jpg","img_width":670,"is_origin":false,"source":0,"text":"
七下2. 4光和颜色(1)
一、光之功
阳光普照,滋润着万物!
","type":1},{"audio_music_id":0,"img_url":"https://ss2.meipian.me/users/2385561/eb6c62aafb964c8c91d701ace8f2e8c2.jpg","is_origin":false,"source":0,"text":"
西塘很美
","type":1},{"audio_music_id":0,"img_url":"https://ss2.meipian.me/users/2385561/7895942d415f462c87cf5efb33f19045.jpg","is_origin":false,"source":0,"type":1},{"audio_music_id":0,"img_url":"https://ss2.meipian.me/users/2385561/918d2b77172a47e9b08ebc279ffd3599.jpg","is_origin":false,"source":0,"type":1},{"audio_music_id":0,"img_height":240,"img_size":208,"img_url":"https://ss2.meipian.me/users/2385561/fd91a79379e29d5b4ea46643f787af42.gif","img_width":369,"is_origin":false,"source":0,"text":"
能看这些美景是因有光:
能看屏幕学习也因有光
思考
","type":1},{"audio_music_id":0,"img_height":123,"img_size":45,"img_url":"https://ss2.meipian.me/users/2385561/cce8583e242cdd7d1e68f20887c91bc2.jpg","img_width":516,"is_origin":false,"source":0,"text":"
你是否看到了燃烧的蜡烛?
为何能看到?
答:因为燃烧的蜡烛有光进入了你的眼睛。
你如果闭上眼睛,你还能看见这些美景、物体与课程吗?为何?
答:不能。没有光进入我们的眼睛了。
我们能看见物体就必须有光从这个物体上进入我们的眼睛。
","type":1},{"audio_music_id":0,"img_height":388,"img_size":61,"img_url":"https://ss2.meipian.me/users/2385561/1e0baaccbc547303109574b94b9a3225.jpg","img_width":628,"is_origin":false,"source":0,"text":"
二、什么是光源
那么光从哪里来?请你向父母描述一下。
父母判断正误
答:光从发光的物体产生。
例如:太阳、火焰、闪电、萤火虫、烛光、正在发光的电灯、正在播放的电视屏幕…
","type":1},{"audio_music_id":0,"img_height":253,"img_size":85,"img_url":"https://ss2.meipian.me/users/2385561/6d163bbfc725f44ea5aa4e9f15aafa7d.jpg","img_width":362,"is_origin":false,"source":0,"text":"
正在发光的物体叫做光源
请你例举一些其它的光源
","type":1},{"audio_music_id":0,"img_height":253,"img_size":67,"img_url":"https://ss2.meipian.me/users/2385561/5ecd9428c4e7a557caab9a43aa9e1c37.jpg","img_width":368,"is_origin":false,"source":0,"type":1},{"audio_music_id":0,"img_height":253,"img_size":53,"img_url":"https://ss2.meipian.me/users/2385561/f2007d61a5f98f08375f670532e80c46.jpg","img_width":410,"is_origin":false,"source":0,"type":1},{"audio_music_id":0,"img_height":240,"img_size":212,"img_url":"https://ss2.meipian.me/users/2385561/3d7e5c6055f29795421303775070905a.gif","img_width":320,"is_origin":false,"source":0,"text":"
(一)自然光源
太阳","type":1},{"audio_music_id":0,"img_height":240,"img_size":199,"img_url":"https://ss2.meipian.me/users/2385561/fcf92359bcf6a36b809a4077a76d6e50.gif","img_width":442,"is_origin":false,"source":0,"text":"
闪电","type":1},{"audio_music_id":0,"img_height":341,"img_size":723,"img_url":"https://ss2.meipian.me/users/2385561/b7189ae418762ecee8005d5467b7518d.gif","img_width":500,"is_origin":false,"source":0,"text":"
萤火虫","type":1},{"audio_music_id":0,"img_height":211,"img_size":621,"img_url":"https://ss2.meipian.me/users/2385561/f8f9421da7aa29218000236007566437.gif","img_width":245,"is_origin":false,"source":0,"text":"
(二)人造光源
火把","type":1},{"audio_music_id":0,"img_height":1500,"img_url":"https://ss2.meipian.me/users/2385561/c87e573a07be241af3e7449fa99683a9.jpg","img_width":1000,"is_origin":false,"source":0,"type":1},{"audio_music_id":0,"img_height":400,"img_size":386,"img_url":"https://ss2.meipian.me/users/2385561/94ac3be9b7cd6270322eb0fce5d37366.gif","img_width":400,"is_origin":false,"source":0,"text":"
发光的电灯","type":1},{"audio_music_id":0,"img_height":115,"img_size":556,"img_url":"https://ss2.meipian.me/users/2385561/74ac77607919e9c7d72d72d22090d651.gif","img_width":277,"is_origin":false,"source":0,"text":"
激光束","type":1},{"audio_music_id":0,"img_height":500,"img_size":404,"img_url":"https://ss2.meipian.me/users/2385561/f7f100f6259352d6dd85b3e7f75f1695.gif","img_width":750,"is_origin":false,"source":0,"type":1},{"audio_music_id":0,"img_height":125,"img_size":50,"img_url":"https://ss2.meipian.me/users/2385561/ad0622cb3bdd9c9533c9bfbb53106992.jpg","img_width":564,"is_origin":false,"source":0,"text":"
很危险不能顺便玩!
(三)请你宣判
月亮、宝石、电影屏幕、镜子等,也会亮的,它们是光源吗?
","type":1},{"audio_music_id":0,"img_height":564,"img_size":76,"img_url":"https://ss2.meipian.me/users/2385561/3d0bea23cba8eec76ddd0190144d70ef.jpg","img_width":755,"is_origin":false,"source":0,"text":"
请向父母描述
父母判断正误
答:不是。因为它们不能自行发光。
三、光的传播
(一)真空能否传播光
声音的传播需要介质,在真空中不能传播。那么光能不能在真空中传播呢?请你好好的动动脑子,然后向父母描述,并说明理由。
父母判断正误
答:太阳与地球之间有很一部分是真空的,太阳光能到达地球。这就说明了光在真空中能够传播。
空气、玻璃、水等透明物质,光也能通过。
结论:光能在真空中传播,也能在透明物质传播。
(二)光的传播路径
1.请用激光 笔做个实验,请将一束激光射到空气中,观察传播路径。
","type":1},{"audio_music_id":0,"img_height":303,"img_size":59,"img_url":"https://ss2.meipian.me/users/2385561/d9492638a217a28a763e705f4faee2ed.jpg","img_width":450,"is_origin":false,"source":0,"text":"
实验结果:光在空气中沿直线传播。
2.请将一束激光射到水中,观察传播路径。
","type":1},{"audio_music_id":0,"img_url":"https://ss2.meipian.me/users/2385561/462002026cbf4fa2bfd591cbe5c70727.jpg","is_origin":false,"source":0,"type":1},{"audio_music_id":0,"img_height":272,"img_width":368,"is_origin":false,"source":0,"source_platform":"local","text":"
实验结果:光在玻璃中沿直线传播。
结论:光在同一种均匀物质中是沿直线传播的。
","type":3,"video_end_time":0,"video_length":205,"video_origin_path":"","video_start_time":0,"video_thumbnail":"http://static2.ivwen.com/users/2385561/1582079516064.jpg","video_url":"http://video.ivwen.com/users/2385561/1582079496907.mp4"},{"audio_music_id":0,"img_height":288,"img_width":512,"is_origin":true,"source":0,"source_platform":"local","text":"光在不均匀介质中传播路线发生弯曲
","type":3,"video_end_time":0,"video_length":55.769,"video_origin_path":"","video_start_time":0,"video_thumbnail":"https://static2.ivwen.com/users/2385561/1647443892399.jpg","video_url":"https://video.ivwen.com/users/2385561/232bc60c363c22b76655240f5b1bdc13.mp4"},{"audio_music_id":0,"img_height":312,"img_size":65,"img_url":"https://ss2.meipian.me/users/2385561/76096702f075019feec93e95daf3bb51.jpg","img_width":550,"is_origin":false,"source":0,"text":"
【思维训练】
西汉大文学家匡衡幼时凿穿墙壁引邻舍之烛光读书,终成一代文学家的故事。现用来形容家贫而读书刻苦的人。匡衡勤学而无烛,邻舍有烛而不逮,衡乃穿壁引其光,以书映光而读之。请你说出“凿壁偷光”包含的科学道理?
","type":1},{"audio_music_id":0,"img_height":293,"img_size":86,"img_url":"https://ss2.meipian.me/users/2385561/777a7aa2337ffbdfc362e23682219e2f.jpg","img_width":449,"is_origin":false,"source":0,"text":"
请向父母叙述
父母判断正误
答:不透明墙遮挡光的传播。光可以在空气中传播。光在空气中沿直线传播。
古人的条件这么艰苦都能这么努力学习,那么我们呢?
(三)光线
为了能更形象的说明光的传播,我们就用一条带箭头的直线表示光的传播路线和方向。
","type":1},{"audio_music_id":0,"img_height":389,"img_size":66,"img_url":"https://ss2.meipian.me/users/2385561/4ff48ce91e3d2caca040269f708c164b.jpg","img_width":300,"is_origin":false,"source":0,"text":"
【思考】
光线真实存在吗?
请向父母叙述
父母判断正误
答:光线实际上是不存在的,只是为了更形象的说明问题科学家引入的一种模型。但光是真实存在的。
四、光直线传播的现象
(一)影子的形成
1.你能解释影子形成原理吗?
","type":1},{"audio_music_id":0,"img_url":"https://ss2.meipian.me/users/2385561/f35c6f982fd148ecbd6277e9bc38f890.jpg","is_origin":false,"source":0,"text":"
请向叙述
父母判断正误
答:光沿直线传播过程中,遇到不透明的物体被挡住,形成暗区,所以产生了影子。
2.当人远离路灯时,影子会怎样变化?
","type":1},{"audio_music_id":0,"img_height":167,"img_size":26,"img_url":"https://ss2.meipian.me/users/2385561/d64bd33530858cddaa968b0df046ecf9.jpg","img_width":554,"is_origin":false,"source":0,"type":1},{"audio_music_id":0,"img_height":439,"img_size":84,"img_url":"https://ss2.meipian.me/users/2385561/afac41c414b56032766b6de43067ecd7.jpg","img_width":622,"is_origin":false,"source":0,"text":"
3.无影灯
","type":1},{"audio_music_id":0,"img_height":345,"img_size":113,"img_url":"https://ss2.meipian.me/users/2385561/origin509436c01c9b5182ff7ac042e6e68e6a.jpg","img_width":500,"is_origin":true,"source":0,"text":"皮影戏
","type":1},{"audio_music_id":0,"img_height":409,"img_size":435,"img_url":"https://ss2.meipian.me/users/2385561/origin42971f49feac16b9cb4fc5d59116bda6.jpg","img_width":649,"is_origin":true,"source":0,"type":1},{"audio_music_id":0,"img_height":311,"img_size":28,"img_url":"https://ss2.meipian.me/users/2385561/origin8abc2f45f7fa98de9adc853e0b8c8e72.jpg","img_width":498,"is_origin":true,"source":0,"type":1},{"audio_music_id":0,"img_height":272,"img_width":368,"is_origin":false,"source":0,"source_platform":"local","text":"
(二).小孔成像
","type":3,"video_end_time":0,"video_length":34,"video_origin_path":"","video_start_time":0,"video_thumbnail":"http://static2.ivwen.com/users/2385561/1582080805702.jpg","video_url":"http://video.ivwen.com/users/2385561/1582080801651.mp4"},{"audio_music_id":0,"img_height":233,"img_size":52,"img_url":"https://ss2.meipian.me/users/2385561/fa2c7832cdac5c033064c7d63d9a70d3.jpg","img_width":579,"is_origin":false,"source":0,"text":"
小孔成像现象说明光在均匀物质中是沿直线传播的。
","type":1},{"audio_music_id":0,"img_height":491,"img_size":82,"img_url":"https://ss2.meipian.me/users/2385561/b6502c8988019b76b209b6abbe7f9186.jpg","img_width":655,"is_origin":false,"source":0,"text":"
1.探究像的形状
","type":1},{"audio_music_id":0,"img_height":384,"img_width":512,"is_origin":true,"source":0,"source_platform":"local","type":3,"video_end_time":0,"video_length":170.467,"video_origin_path":"/storage/emulated/0/QQBrowser/视频/mp_1647495632360.weixin.qq.mp4","video_start_time":0,"video_thumbnail":"https://static2.ivwen.com/users/2385561/1647495682210.jpg","video_url":"https://video.ivwen.com/users/2385561/cd2bb7647b5e9ad6b337ea521964a7fc.mp4"},{"audio_music_id":0,"img_height":249,"img_size":70,"img_url":"https://ss2.meipian.me/users/2385561/86a1ae5646561587cdfd82d979932244.jpg","img_width":574,"is_origin":false,"source":0,"text":"
2.成像性质
你能说一下小孔成像的像的性质(正立还是倒立、虚像还是实像、放大还是缩小)吗?
请动手认真的探究一下
再向父母描述
父母判断正误
答:1.所成像是倒立的(像上下颠倒、左右颠倒);
2.所成像是实像,因为一则像由实际光线形成;二则像可以在屏中呈现;
3.所成像大小由物距(U)与像距(V)的大小决定。
当U>V时成缩小的像;
当U<Ⅴ时成放大的像。
当U=v时?
","type":1},{"audio_music_id":0,"img_height":720,"img_width":1280,"is_origin":false,"source":0,"source_platform":"local","type":3,"video_end_time":0,"video_length":495,"video_origin_path":"","video_start_time":0,"video_thumbnail":"http://static2.ivwen.com/users/2385561/1582266656779.jpg","video_url":"http://video.ivwen.com/users/2385561/1582266454963.mp4"},{"audio_music_id":0,"img_height":445,"img_size":51,"img_url":"https://ss2.meipian.me/users/2385561/865fe8991021e9c072957fce4ee0dd08.jpg","img_width":554,"is_origin":false,"source":0,"text":"
(三)日食、月食现象
光在真空中沿直线传播。日全食:我们观察者刚好在月球的影子中。月全食:月球绕进了地球的影子里。
","type":1},{"audio_music_id":0,"img_height":135,"img_size":45,"img_url":"https://ss2.meipian.me/users/2385561/b1f72285b14f6464f90bd57397980869.jpg","img_width":487,"is_origin":false,"source":0,"text":"
(四)光线准直
光在同一种均匀物质中沿直线传播。
(1)激光准直仪
","type":1},{"audio_music_id":0,"img_height":72,"img_size":12,"img_url":"https://ss2.meipian.me/users/2385561/ba030f3bb69ba2b43533a990e0bde2f0.jpg","img_width":311,"is_origin":false,"source":0,"text":"
(2)打靶瞄准
用步枪瞄准射击时,当眼睛看到瞄准点、准星尖和缺口三者重合时,就认为三者处于同一直线上了。
","type":1},{"audio_music_id":0,"img_height":300,"img_size":89,"img_url":"https://ss2.meipian.me/users/2385561/78e95b7c1df0a8da6b10c33af490c183.jpg","img_width":500,"is_origin":false,"source":0,"text":"(3)排队看齐
利用光的直线传播就能让队伍更整齐。
","type":1},{"audio_music_id":0,"img_height":300,"img_size":64,"img_url":"https://ss2.meipian.me/users/2385561/c1095a4712defa9b29c5c8f89e16869a.jpg","img_width":500,"is_origin":false,"source":0,"type":1},{"audio_music_id":0,"img_height":300,"img_size":44,"img_url":"https://ss2.meipian.me/users/2385561/4484de23e7884156250b03d1f24169b5.jpg","img_width":500,"is_origin":false,"source":0,"type":1},{"audio_music_id":0,"img_height":3024,"img_size":1249,"img_url":"https://ss2.meipian.me/users/2385561/origin4d79e25294fba3cde67a9560239be1ea.jpg","img_width":4032,"is_origin":true,"source":0,"type":1},{"audio_music_id":0,"img_height":482,"img_size":92,"img_url":"https://ss2.meipian.me/users/2385561/351f3cda46ae89ac3073270830fc115f.jpg","img_width":592,"is_origin":false,"source":0,"text":"(五)、小结
","type":1},{"audio_music_id":0,"img_height":600,"img_size":105,"img_url":"https://ss2.meipian.me/users/2385561/b4bcd990cfc1fba2d5e4552708ce4588.gif","img_width":600,"is_origin":false,"source":0,"text":"六、练习
1.下列四个词语所描述的光现象中,表示能自行发光的是------( )
A、金光闪闪 B、红光满面
C、火光冲天 D、波光粼粼
2.下列现象中,是由于光沿直线传播形成的
A、阳光下的树影 B、父亲的背影( )
C、平静水面中的倒影 D、水中的鱼
3.人沿着街道走向街灯,再从街灯走远,则他的影子长短变化是---( )
A、变长 B、先变长再变短
C、变短 D、先变短再变长
4.下列关于光线的说法正确的是---------( )
A、光线是我们假想的线,其实是不存在的
B、把一束光缩小,就成了光线;
C、一个光源只能发出一条光线;
D、光线是真实存在的。
5.下列说法正确的是-----------( )
A、无影灯下没有影,光可以透过一切障碍物;
B、无影灯下没有影,因为光没有沿直线传播;
C、无影灯下没有影,因为一盏灯发出的光产生的影被其他灯发出的光照明;
D、无影灯下没有影,因无影灯比普通灯亮得多。
请拿出纸笔认真练习。
做好后请交给家长批改
家长按标准答案批改!
答案
1.C 2.A 3.D 4.A 5.C
","type":1}]},"ext":{"id":123258365,"article_id":212981784,"ip":"122.225.62.154","origin_status":0,"edit_from":0,"client_type":2,"password_v2":"","uv":1,"font_id":0,"title_style":"{\"text_color\":{\"color\":\"#191919\",\"index\":0},\"text_size\":\"large\",\"text_style\":[\"bold\"]}","rich_text_title":"","gift_switch":1,"deleted_at":0,"recycle_expired_at":0,"share_with_nickname":1,"enable_watermark":2,"music_id":0,"music_source":0,"_auto_update_time":"2022-06-09 15:27:54"},"extend":{"id":43755198,"article_id":212981784,"enable_download":1,"cover_width":670,"cover_height":390}},"author":{"id":"2385561","nickname":"LjX","head_img_url":"https://ss2.meipian.me/users/2385561/53d1f6b84c76400aaec4eea445e57e44.jpg","column_visit":26041,"signature":"LjX","favorite_count":534,"follow_count":25928,"follower_count":15129,"famous_type":0,"autoplay_music":1,"text_preference":1,"client_type":0,"reward_word":"如果喜欢我的作品,请打赏鼓励哦!","member_type":0,"wechat_id":"ojq1tt41OArdrQVMULlW2Yc5-RkU","country":"中国","province":"浙江","city":"嘉兴","career":9,"birthday":19660808,"gender":1,"reg_time":1465511901,"e_id":"","bedge_img":"","label_img":"","review_level":1,"token":"cdbe017d0cf30c8ae85f3a9f41b6bdbc","enable_reward_switch":false,"enable_water_mark_switch":0,"plainNickname":"LjX","member_status":2,"member_img":"https://ss2.meipian.me/app/member/icon/member2.png","ext":null,"head_attach_img":null,"badge":null,"onlive":false,"qualification":null,"biz_info":{"is_biz_user":false,"share_domains":[]},"headwear":{"icon":"https://ss2.meipian.me/app/badge/newyear2024/long_gate_for_fish.webp","animation":"","config":{"replace":null},"param":{"n":0,"num_desc":""}},"cover_img_url":"https://ss2.meipian.me/users/2385561/01627ff5ca9040a79b0c644a2501166b.jpg","weibo_id":"","vwen_id":"5a80594432fdd138fa901cbb913db9d2","im_id":"fdb4e9bee3e628f9749787319dcde927","yx_im_token":"","last_visit_time":1711687785,"login_token":"78_oK2rbKVI9zZOMm0uMepObEmsRj1iaLmvsGixjaj5bvYSXzBQPwZOuvJtq1WYqTz3GetrkybXaF9CUgB3knyy9NTDK6p86hpGx4-1PYBqLck","ip_address":"122.225.63.169","phone_num":"15355213979","device_id":"703aac5ff08764d6:02:00:00:00:00:00","reviewer":0,"review_time":0,"account_state":0,"balance":2330,"last_contribution_time":1509783923,"member_expire_time":0,"member_qq_group":0,"web_has_login":1,"longtitude":"121.3473200","latitude":"30.2671150","last_client_type":0,"level":0,"province_user":"北京","city_user":"不限","user_id":2385561,"qq_id":"","apple_id":"","badge_img_url":"","reward_url":"https://www.meipian.cn/wap/reward/view/index.html?mask_id=2pubusib&author_user_id=2385561&article_title=%E6%B5%99%E6%95%99%E7%89%88%E7%A7%91%E5%AD%A6%E4%B8%83%E4%B8%8B2.4%281%29","memo_name":""},"content":[{"audio_music_id":0,"img_height":390,"img_size":76,"img_url":"https://ss2.meipian.me/users/2385561/4e5237b973fb420d429492bb3a9f774d.jpg","img_width":670,"is_origin":false,"source":0,"text":"
七下2. 4光和颜色(1)
一、光之功
阳光普照,滋润着万物!
","type":1},{"audio_music_id":0,"img_url":"https://ss2.meipian.me/users/2385561/eb6c62aafb964c8c91d701ace8f2e8c2.jpg","is_origin":false,"source":0,"text":"
西塘很美
","type":1},{"audio_music_id":0,"img_url":"https://ss2.meipian.me/users/2385561/7895942d415f462c87cf5efb33f19045.jpg","is_origin":false,"source":0,"type":1},{"audio_music_id":0,"img_url":"https://ss2.meipian.me/users/2385561/918d2b77172a47e9b08ebc279ffd3599.jpg","is_origin":false,"source":0,"type":1},{"audio_music_id":0,"img_height":240,"img_size":208,"img_url":"https://ss2.meipian.me/users/2385561/fd91a79379e29d5b4ea46643f787af42.gif","img_width":369,"is_origin":false,"source":0,"text":"
能看这些美景是因有光:
能看屏幕学习也因有光
思考
","type":1},{"audio_music_id":0,"img_height":123,"img_size":45,"img_url":"https://ss2.meipian.me/users/2385561/cce8583e242cdd7d1e68f20887c91bc2.jpg","img_width":516,"is_origin":false,"source":0,"text":"
你是否看到了燃烧的蜡烛?
为何能看到?
答:因为燃烧的蜡烛有光进入了你的眼睛。
你如果闭上眼睛,你还能看见这些美景、物体与课程吗?为何?
答:不能。没有光进入我们的眼睛了。
我们能看见物体就必须有光从这个物体上进入我们的眼睛。
","type":1},{"audio_music_id":0,"img_height":388,"img_size":61,"img_url":"https://ss2.meipian.me/users/2385561/1e0baaccbc547303109574b94b9a3225.jpg","img_width":628,"is_origin":false,"source":0,"text":"
二、什么是光源
那么光从哪里来?请你向父母描述一下。
父母判断正误
答:光从发光的物体产生。
例如:太阳、火焰、闪电、萤火虫、烛光、正在发光的电灯、正在播放的电视屏幕…
","type":1},{"audio_music_id":0,"img_height":253,"img_size":85,"img_url":"https://ss2.meipian.me/users/2385561/6d163bbfc725f44ea5aa4e9f15aafa7d.jpg","img_width":362,"is_origin":false,"source":0,"text":"
正在发光的物体叫做光源
请你例举一些其它的光源
","type":1},{"audio_music_id":0,"img_height":253,"img_size":67,"img_url":"https://ss2.meipian.me/users/2385561/5ecd9428c4e7a557caab9a43aa9e1c37.jpg","img_width":368,"is_origin":false,"source":0,"type":1},{"audio_music_id":0,"img_height":253,"img_size":53,"img_url":"https://ss2.meipian.me/users/2385561/f2007d61a5f98f08375f670532e80c46.jpg","img_width":410,"is_origin":false,"source":0,"type":1},{"audio_music_id":0,"img_height":240,"img_size":212,"img_url":"https://ss2.meipian.me/users/2385561/3d7e5c6055f29795421303775070905a.gif","img_width":320,"is_origin":false,"source":0,"text":"
(一)自然光源
太阳","type":1},{"audio_music_id":0,"img_height":240,"img_size":199,"img_url":"https://ss2.meipian.me/users/2385561/fcf92359bcf6a36b809a4077a76d6e50.gif","img_width":442,"is_origin":false,"source":0,"text":"
闪电","type":1},{"audio_music_id":0,"img_height":341,"img_size":723,"img_url":"https://ss2.meipian.me/users/2385561/b7189ae418762ecee8005d5467b7518d.gif","img_width":500,"is_origin":false,"source":0,"text":"
萤火虫","type":1},{"audio_music_id":0,"img_height":211,"img_size":621,"img_url":"https://ss2.meipian.me/users/2385561/f8f9421da7aa29218000236007566437.gif","img_width":245,"is_origin":false,"source":0,"text":"
(二)人造光源
火把","type":1},{"audio_music_id":0,"img_height":1500,"img_url":"https://ss2.meipian.me/users/2385561/c87e573a07be241af3e7449fa99683a9.jpg","img_width":1000,"is_origin":false,"source":0,"type":1},{"audio_music_id":0,"img_height":400,"img_size":386,"img_url":"https://ss2.meipian.me/users/2385561/94ac3be9b7cd6270322eb0fce5d37366.gif","img_width":400,"is_origin":false,"source":0,"text":"
发光的电灯","type":1},{"audio_music_id":0,"img_height":115,"img_size":556,"img_url":"https://ss2.meipian.me/users/2385561/74ac77607919e9c7d72d72d22090d651.gif","img_width":277,"is_origin":false,"source":0,"text":"
激光束","type":1},{"audio_music_id":0,"img_height":500,"img_size":404,"img_url":"https://ss2.meipian.me/users/2385561/f7f100f6259352d6dd85b3e7f75f1695.gif","img_width":750,"is_origin":false,"source":0,"type":1},{"audio_music_id":0,"img_height":125,"img_size":50,"img_url":"https://ss2.meipian.me/users/2385561/ad0622cb3bdd9c9533c9bfbb53106992.jpg","img_width":564,"is_origin":false,"source":0,"text":"
很危险不能顺便玩!
(三)请你宣判
月亮、宝石、电影屏幕、镜子等,也会亮的,它们是光源吗?
","type":1},{"audio_music_id":0,"img_height":564,"img_size":76,"img_url":"https://ss2.meipian.me/users/2385561/3d0bea23cba8eec76ddd0190144d70ef.jpg","img_width":755,"is_origin":false,"source":0,"text":"
请向父母描述
父母判断正误
答:不是。因为它们不能自行发光。
三、光的传播
(一)真空能否传播光
声音的传播需要介质,在真空中不能传播。那么光能不能在真空中传播呢?请你好好的动动脑子,然后向父母描述,并说明理由。
父母判断正误
答:太阳与地球之间有很一部分是真空的,太阳光能到达地球。这就说明了光在真空中能够传播。
空气、玻璃、水等透明物质,光也能通过。
结论:光能在真空中传播,也能在透明物质传播。
(二)光的传播路径
1.请用激光 笔做个实验,请将一束激光射到空气中,观察传播路径。
","type":1},{"audio_music_id":0,"img_height":303,"img_size":59,"img_url":"https://ss2.meipian.me/users/2385561/d9492638a217a28a763e705f4faee2ed.jpg","img_width":450,"is_origin":false,"source":0,"text":"
实验结果:光在空气中沿直线传播。
2.请将一束激光射到水中,观察传播路径。
","type":1},{"audio_music_id":0,"img_url":"https://ss2.meipian.me/users/2385561/462002026cbf4fa2bfd591cbe5c70727.jpg","is_origin":false,"source":0,"type":1},{"audio_music_id":0,"img_height":272,"img_width":368,"is_origin":false,"source":0,"source_platform":"local","text":"
实验结果:光在玻璃中沿直线传播。
结论:光在同一种均匀物质中是沿直线传播的。
","type":3,"video_end_time":0,"video_length":205,"video_origin_path":"","video_start_time":0,"video_thumbnail":"http://static2.ivwen.com/users/2385561/1582079516064.jpg","video_url":"http://video.ivwen.com/users/2385561/1582079496907.mp4"},{"audio_music_id":0,"img_height":288,"img_width":512,"is_origin":true,"source":0,"source_platform":"local","text":"光在不均匀介质中传播路线发生弯曲
","type":3,"video_end_time":0,"video_length":55.769,"video_origin_path":"","video_start_time":0,"video_thumbnail":"https://static2.ivwen.com/users/2385561/1647443892399.jpg","video_url":"https://video.ivwen.com/users/2385561/232bc60c363c22b76655240f5b1bdc13.mp4"},{"audio_music_id":0,"img_height":312,"img_size":65,"img_url":"https://ss2.meipian.me/users/2385561/76096702f075019feec93e95daf3bb51.jpg","img_width":550,"is_origin":false,"source":0,"text":"
【思维训练】
西汉大文学家匡衡幼时凿穿墙壁引邻舍之烛光读书,终成一代文学家的故事。现用来形容家贫而读书刻苦的人。匡衡勤学而无烛,邻舍有烛而不逮,衡乃穿壁引其光,以书映光而读之。请你说出“凿壁偷光”包含的科学道理?
","type":1},{"audio_music_id":0,"img_height":293,"img_size":86,"img_url":"https://ss2.meipian.me/users/2385561/777a7aa2337ffbdfc362e23682219e2f.jpg","img_width":449,"is_origin":false,"source":0,"text":"
请向父母叙述
父母判断正误
答:不透明墙遮挡光的传播。光可以在空气中传播。光在空气中沿直线传播。
古人的条件这么艰苦都能这么努力学习,那么我们呢?
(三)光线
为了能更形象的说明光的传播,我们就用一条带箭头的直线表示光的传播路线和方向。
","type":1},{"audio_music_id":0,"img_height":389,"img_size":66,"img_url":"https://ss2.meipian.me/users/2385561/4ff48ce91e3d2caca040269f708c164b.jpg","img_width":300,"is_origin":false,"source":0,"text":"
【思考】
光线真实存在吗?
请向父母叙述
父母判断正误
答:光线实际上是不存在的,只是为了更形象的说明问题科学家引入的一种模型。但光是真实存在的。
四、光直线传播的现象
(一)影子的形成
1.你能解释影子形成原理吗?
","type":1},{"audio_music_id":0,"img_url":"https://ss2.meipian.me/users/2385561/f35c6f982fd148ecbd6277e9bc38f890.jpg","is_origin":false,"source":0,"text":"
请向叙述
父母判断正误
答:光沿直线传播过程中,遇到不透明的物体被挡住,形成暗区,所以产生了影子。
2.当人远离路灯时,影子会怎样变化?
","type":1},{"audio_music_id":0,"img_height":167,"img_size":26,"img_url":"https://ss2.meipian.me/users/2385561/d64bd33530858cddaa968b0df046ecf9.jpg","img_width":554,"is_origin":false,"source":0,"type":1},{"audio_music_id":0,"img_height":439,"img_size":84,"img_url":"https://ss2.meipian.me/users/2385561/afac41c414b56032766b6de43067ecd7.jpg","img_width":622,"is_origin":false,"source":0,"text":"
3.无影灯
","type":1},{"audio_music_id":0,"img_height":345,"img_size":113,"img_url":"https://ss2.meipian.me/users/2385561/origin509436c01c9b5182ff7ac042e6e68e6a.jpg","img_width":500,"is_origin":true,"source":0,"text":"皮影戏
","type":1},{"audio_music_id":0,"img_height":409,"img_size":435,"img_url":"https://ss2.meipian.me/users/2385561/origin42971f49feac16b9cb4fc5d59116bda6.jpg","img_width":649,"is_origin":true,"source":0,"type":1},{"audio_music_id":0,"img_height":311,"img_size":28,"img_url":"https://ss2.meipian.me/users/2385561/origin8abc2f45f7fa98de9adc853e0b8c8e72.jpg","img_width":498,"is_origin":true,"source":0,"type":1},{"audio_music_id":0,"img_height":272,"img_width":368,"is_origin":false,"source":0,"source_platform":"local","text":"
(二).小孔成像
","type":3,"video_end_time":0,"video_length":34,"video_origin_path":"","video_start_time":0,"video_thumbnail":"http://static2.ivwen.com/users/2385561/1582080805702.jpg","video_url":"http://video.ivwen.com/users/2385561/1582080801651.mp4"},{"audio_music_id":0,"img_height":233,"img_size":52,"img_url":"https://ss2.meipian.me/users/2385561/fa2c7832cdac5c033064c7d63d9a70d3.jpg","img_width":579,"is_origin":false,"source":0,"text":"
小孔成像现象说明光在均匀物质中是沿直线传播的。
","type":1},{"audio_music_id":0,"img_height":491,"img_size":82,"img_url":"https://ss2.meipian.me/users/2385561/b6502c8988019b76b209b6abbe7f9186.jpg","img_width":655,"is_origin":false,"source":0,"text":"
1.探究像的形状
","type":1},{"audio_music_id":0,"img_height":384,"img_width":512,"is_origin":true,"source":0,"source_platform":"local","type":3,"video_end_time":0,"video_length":170.467,"video_origin_path":"/storage/emulated/0/QQBrowser/视频/mp_1647495632360.weixin.qq.mp4","video_start_time":0,"video_thumbnail":"https://static2.ivwen.com/users/2385561/1647495682210.jpg","video_url":"https://video.ivwen.com/users/2385561/cd2bb7647b5e9ad6b337ea521964a7fc.mp4"},{"audio_music_id":0,"img_height":249,"img_size":70,"img_url":"https://ss2.meipian.me/users/2385561/86a1ae5646561587cdfd82d979932244.jpg","img_width":574,"is_origin":false,"source":0,"text":"
2.成像性质
你能说一下小孔成像的像的性质(正立还是倒立、虚像还是实像、放大还是缩小)吗?
请动手认真的探究一下
再向父母描述
父母判断正误
答:1.所成像是倒立的(像上下颠倒、左右颠倒);
2.所成像是实像,因为一则像由实际光线形成;二则像可以在屏中呈现;
3.所成像大小由物距(U)与像距(V)的大小决定。
当U>V时成缩小的像;
当U<Ⅴ时成放大的像。
当U=v时?
","type":1},{"audio_music_id":0,"img_height":720,"img_width":1280,"is_origin":false,"source":0,"source_platform":"local","type":3,"video_end_time":0,"video_length":495,"video_origin_path":"","video_start_time":0,"video_thumbnail":"http://static2.ivwen.com/users/2385561/1582266656779.jpg","video_url":"http://video.ivwen.com/users/2385561/1582266454963.mp4"},{"audio_music_id":0,"img_height":445,"img_size":51,"img_url":"https://ss2.meipian.me/users/2385561/865fe8991021e9c072957fce4ee0dd08.jpg","img_width":554,"is_origin":false,"source":0,"text":"
(三)日食、月食现象
光在真空中沿直线传播。日全食:我们观察者刚好在月球的影子中。月全食:月球绕进了地球的影子里。
","type":1},{"audio_music_id":0,"img_height":135,"img_size":45,"img_url":"https://ss2.meipian.me/users/2385561/b1f72285b14f6464f90bd57397980869.jpg","img_width":487,"is_origin":false,"source":0,"text":"
(四)光线准直
光在同一种均匀物质中沿直线传播。
(1)激光准直仪
","type":1},{"audio_music_id":0,"img_height":72,"img_size":12,"img_url":"https://ss2.meipian.me/users/2385561/ba030f3bb69ba2b43533a990e0bde2f0.jpg","img_width":311,"is_origin":false,"source":0,"text":"
(2)打靶瞄准
用步枪瞄准射击时,当眼睛看到瞄准点、准星尖和缺口三者重合时,就认为三者处于同一直线上了。
","type":1},{"audio_music_id":0,"img_height":300,"img_size":89,"img_url":"https://ss2.meipian.me/users/2385561/78e95b7c1df0a8da6b10c33af490c183.jpg","img_width":500,"is_origin":false,"source":0,"text":"(3)排队看齐
利用光的直线传播就能让队伍更整齐。
","type":1},{"audio_music_id":0,"img_height":300,"img_size":64,"img_url":"https://ss2.meipian.me/users/2385561/c1095a4712defa9b29c5c8f89e16869a.jpg","img_width":500,"is_origin":false,"source":0,"type":1},{"audio_music_id":0,"img_height":300,"img_size":44,"img_url":"https://ss2.meipian.me/users/2385561/4484de23e7884156250b03d1f24169b5.jpg","img_width":500,"is_origin":false,"source":0,"type":1},{"audio_music_id":0,"img_height":3024,"img_size":1249,"img_url":"https://ss2.meipian.me/users/2385561/origin4d79e25294fba3cde67a9560239be1ea.jpg","img_width":4032,"is_origin":true,"source":0,"type":1},{"audio_music_id":0,"img_height":482,"img_size":92,"img_url":"https://ss2.meipian.me/users/2385561/351f3cda46ae89ac3073270830fc115f.jpg","img_width":592,"is_origin":false,"source":0,"text":"(五)、小结
","type":1},{"audio_music_id":0,"img_height":600,"img_size":105,"img_url":"https://ss2.meipian.me/users/2385561/b4bcd990cfc1fba2d5e4552708ce4588.gif","img_width":600,"is_origin":false,"source":0,"text":"六、练习
1.下列四个词语所描述的光现象中,表示能自行发光的是------( )
A、金光闪闪 B、红光满面
C、火光冲天 D、波光粼粼
2.下列现象中,是由于光沿直线传播形成的
A、阳光下的树影 B、父亲的背影( )
C、平静水面中的倒影 D、水中的鱼
3.人沿着街道走向街灯,再从街灯走远,则他的影子长短变化是---( )
A、变长 B、先变长再变短
C、变短 D、先变短再变长
4.下列关于光线的说法正确的是---------( )
A、光线是我们假想的线,其实是不存在的
B、把一束光缩小,就成了光线;
C、一个光源只能发出一条光线;
D、光线是真实存在的。
5.下列说法正确的是-----------( )
A、无影灯下没有影,光可以透过一切障碍物;
B、无影灯下没有影,因为光没有沿直线传播;
C、无影灯下没有影,因为一盏灯发出的光产生的影被其他灯发出的光照明;
D、无影灯下没有影,因无影灯比普通灯亮得多。
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答案
1.C 2.A 3.D 4.A 5.C
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