Thiết kế bài giảng vật lí 12 nâng cao (tập 2) phần 1

TRAN THUY HANG - HA DUYEN TUNG THIET KE BAI GIANG NANG CAO TAP HA! NHAXUATBANHANOI TRAN THUY H A N G - H A DUY£N TUNG THIET KE BAI GIANG lAVt NANG CAO - TAP ^ V- ? NHA XUAT BAN HA NOI CHWONG V DONG DIEN XOAY CHIEU • BAI26 DONG DifiN XOAY CHlfiu MACH DifiN XOAY CHlfiu CHI CO DifiN TRO T H U A N I-MUCTlfiU Ve kie'n thiic - Nam ducfc khai niem dong di6n xoay chi^u va di6n ap xoay chi^u Biet each xac dinh ,d6 l6ch pha gii5a dien ap va circfng dong didn xoay chieu theo bi^u thiic hoac theo thi bi^u di6n chiing - Nam duoc cac dac didm cua doan mach xoay chieu chi co di£n trd thu^n ~ Nam duoc cac gia tri hi6u dung va each tinh cong suat toa nhi6t trung binh cua dong di6n xoay chi^u Ve ki n i n g - Ren luyen ki nang quan sat GV tid'n hanh thi nghiem co sit dung dao d6ng ki dien tif, tit riit cac k6't luan cua bai hoc II-CHUXNBI Gido vien - Chu^n bi mo hinh may phat dien xoay chi6u va dien k6' - Dao d6ng ki dien tir, ngudn dien xoay chi^u hoc sinh, may phat am tan Hpc sinh - On lai cac kiah thiic ve dinh luat Om va hien tucmg cam ling di6n ttr da hoc ldp 11 THPT Ill - THI^T K f H O A T D N G DAY H O C Hoat d6ng cua hoc sinh Hoat ddng Kiem tra, chu^n b| dieu kien xuat phat HS suy nghl ca nhan tim cau tra Icri - Khi tiir thong qua mat gicfi han boi mach dien km bien doi theo thcfi gian Trd giup cua giao vi#n GV neu cau hoi kidm tra kien thiic cu - Hi6n tuong cam utig di6n tix xay nao ? - Khi do, goc a bi6'n thi6n theo th6i gian, suy ttr th6ng qua mat gi6i han bcri khung day kin bia'n thien theo thcfi gian Vi vay day xua't hi6n m6t suat difen dong cam ling - Khi cho khung day quay deu tit trucmg vdi t6'c goc co nhu hmh ve sau day, khung co sua't hi6n sua't di6n dong cam ling khong ? Tai ? - Quan sat tha'y kim cua dien ke dao dong sang phai roi sang trai m6t each tu^n hoan Chiing to su^t dien d6ng khung day bi^n thi6n tudn hoan - Yeu c^u HS quan sat GV tien hanh thi nghi6m v6i mo hinh may phat dien xoay chieu co noi v6i dien ke G, sau dua nhan xet ve gia trj cua suat dien d6ng cua may phat dien xoay chieu ? GV thong bao - Sua't diSn dong xua't hien khung day bie'n doi theo thcfi gian theo dinh luat dang sin, thucmg goi tat la sua't di6n d6ng xoay chieu : e = EQ cos(cot + (po) HS tiep thu, ghi nhd - Chu ki va tSn s6' cua bien doi cua suat di6n dong lien he vdfi tan so goc co bdi , „ 271 „ CO cac cong thuc: = — , i = CO 2n - Sua't dien d6ng tao bdi may phat dien xoay chieu cung co bidu thiic dang nhu tren Hoat dong Tim hieu dien ap xoay chieu va dong dien xoay chieu - Khi do, mach co dao d6ng dien cudng biic vdi t^n sd ciia suat dien d6ng may phat di6n xoay chieu tao Giua hai dSu d o ^ mach cd m6t dien ap bi6'n thi6n theo thdi gian theo dinh luat dang sin HS quan sat GV tia'n hanh thi nghiem vdi dao dong ki dien tu - Do thi cua didn ap tren hai d^u mach dien cd dang hinh sin GV neu cau hoi dd HS tim hidu dien ap xoay chieu - Neu ndi hai cue cua may phdt dien xoay chidu vdi mot doan mach ti6u thu di6n thi dien ap giiia hai ddu doan mach cd bidu thiic nhu tha' nao ? GV neu cac cau hoi goi y - Nhan xet gi vd dao dOng dian mach tiau thu ? - Lam thi nghifm nghiem nhu th6' nao dd kidm tra ? GV tien hanh thi nghiem va yfeu eiu HS quan sat dd nit nhan xet GV thdng bao - Trong trudng hop t6ng quat, bidu thiic cLia dien ap gifia hai dau doan mach xoay chidu AB va cudng dd dong dian qua nd cd dang : u = UoCos(cot + (p]) i = lQCos(cot + (p2) - Dai luong cp = cpj -cpj goi la lach pha cua u so vdi i Na'u cp > thi u sdni pha so vdi i Neu (p < thi u trd pha so vdi i Na'u

• • • - ; : HS thao luan ehung toan ldp • - Cho chum tia catdt dng i phong tia catdt dap vao mpt mieng \ kim loai cd nguyan tfl lupng ldn se i phat tia X mden 10" m (ngdn hon budc sdng cua tia tfl ngoai) dupe gpi la tia X hay tia Ron- ghen - Ngudi ta cung thudng phan biat tia X cflng (ed budc sdng rait ngdn) va tia X mdm (cd budc sdng dai hon) GV nau cau hdi dd HS tim hieu each tao tia Ron-ghen - Cd thd tao tia X bdng each nao ? GV thdng bao HS tidp thu, ghi nhd Nha bac hpe Rcm-ghen la ngudi ddu tian da tao tia X nam 1895 bang each 6ng thdy rdng tia X cd tac dung lam phat quang mpt sd chdt va lam den phim anh Va tia X cdn dupe gpi la tia Ron-ghen HS thao luan ehung toan ldp - Tia X ed kha nang dam xuyan ldn : - Tia X tac dung manh lan phim ; anh - Tia X cd tac dung lam phat i quang mpt sd ehdt ; GV nau cau hdi dd HS tim hieu cae tinh chat cua tia X va edng dung eua nd - Hay nau mpt sd tinh chdt cua tia X va fltig dung eua nd ma em bie't 121 - Tia X ed tac dung sinh li manh: buy diet te bao Ngudi ta dung tia X dd : chieu, chup dien de chudn doan banh hoac tim ehd xucfng gay, manh kim loai ngudi HS tia'p thu, ghi nhd Hoat dong Tim hieu thuyet dien tfl ve anh sang HS lam viec ca nhan tim eau tra ldi - Nha bac hpc Mdc-xoen da dya vao sy tuong ty gifla cac tinh chat CLia sdng dien tfl va anh sang va phat tridn thuyet sdng anh sang ciaa Huy-ghen va Fren-nen - Ban chat anh sang : anh sang la sdng dien tfl cd budc sdng rdt ngdn (so vdi sdng vo tuyen dien), lan truydn khong gian 122 GV bd sung kidn thflc - Tia X cd kha nang ddm xuyan ldn, ed the xuyan qua tam nhom day vai xentimet nhung lai bj ldp chi day vai milimet chan lai Vi vay ngudi ta thudng dung chi dd lam cac man chdn tia X Tia X cd budc sdng cang ngan thi cang xuyan sau, tfle la cang cflng - Vi tia X cd tac dung sinh li manh nan ngudi ta edn sfl dung nd dd diet khudn, chfla benh - Tia X edn dupe dung cdng nghiep de kidm tra cac vet nflt, cac bpt ban cae vat bang kim loai, kidm tra hanh li eua hanh khach di may bay, nghian cflu cdu true vat ran GV yau cdu HS dpc mue SGK va tra ldi cae eau hdi sau day de tim hidu thuyet dien tfl ve anh sang - Ai la ngudi dua thuydt dian tfl vd anh sang ? C ^ cfl vao dau de dua thuyet dien tfl vd anh sang ? - Theo thuyet dien tfl vd anh sang thi ban chdt anh sang la gi ? - Tfl thuya't dien tfl vd anh sang, Mac-xoen cung da thiet lap dupe mdi lian he gifla tinh chat dien tfl, vdi tinh chat quang cua mdi trudng - Mdi ban he gifla tinh chat dien tfl vdi tinh chat quang cua mdi trudng la gi ? V dd c la tde dp anh sang chan khdng ; v la tde dp anh sang mdi trudng cd hdng sd dien moi E va dp tfl tham fi - Do tfl thdm cua mdi trudng dupe bang ti sd cua cam img tfl mdi trudng dd va cam flng tfl chan khdng eung mpt ddng dian gay - Hay cho biet dp tfl thdm cua mdi trudng dupe xac djnh nhu the nao ? Dp tfl thdm eua khdng va dp tfl thdm cua cha't sat tfl khae nhu the nao ? - D6 tfl tham eua khong )a = 1, cdn dp tfl thdm ciaa chdt sdt tfl p,»l n = ^ep, - Lo-ren-xo chflng td dupe rang e phu thupc vao tdn sd f cua anh sang £ = F(f) Nhd dd ma dng da giai thich dupe sy tan sdc anh sang - Cae kdt qua tran da dupe thyc nghiam chflng minh - Chiet sudt eua mdi trudng phu thupc nhu the nao vao hang sd dien mdi va dp tfl thdm eua mdi trudng ? - Lo-ren-xo edn chflng td dupe didu gi ? - Cho den nay, cac ket qua tran da dupe chflng minh bang thyc nghiem chua? Hoat ddng Nhin tdng quat ve sdng dien tfl Tim hieu thang sdng dien tfl HS thao luan ehung toan ldp GV neu cau hdi dd HS tim hidu each nhin tdng quat ve sdng dien tfl va tim hidu thang sdng dien tfl 123 HS quan sat thang sdng dian tfl dd kiem tra cae sdng dien tfl vfla het ka - Hay kd tan eae sdng dien tfl ma em ; bie't theo thfl ty sdng dian tfl ed budc sdng tfl ldn den be? GV cho HS quan sat hinh ve 41.3 vd thang sdng dien tfl de kiem tra GV bd sung kien thflc - Trong thang sdng dien tfl, tia gamma ed budc sdng nhd nhdt, tia se dupe hpe d chuong VII - Vi cac tia ed tdn sd va budc sdng khae nan ehung cung cd nhirng tinh chat rdt khae Cae tia cd budc sdng cang ngdn cd tinh dam xuyan cang manh, dd tac dung lan kinh anh, dd lam phat quang eae chat va dd idn hoa khdng Cae tia ed budc sdng dai, ta da quan sat hipn tupng giao thoa HS tia'p thu, ghi nhd Hoat ddng Cung cd bai hpc va dinh hudng nhiem vu hpc tap tiep theo GV yau cdu HS lam cac bai tap phieu hex: tap dd cung cd bai hpc ~ HS ve nha lam eae bai tap 1, SGK - On lai cac kidn thflc vd khoang van, budc sdng anh sang va budc sdng anh sang bang phucmg phap giao thoa PHlfiu HOC TAP cau Budi tdi ed thd chup anh eo thd eon ngudi vi d nhiet dp 37°C co thd ngudi cd the phat cac tia A tia hdng ngoai B tia tfl ngoai C tia Ron-ghen D anh sang nhin thay 124 Can Dieu nao sai so sanh tia hdng ngoai, tfl ngoai va tia Rcm-ghen ? A Cung cd ban cha't la sdng dian tfl B Ca ba loai tia tran ddu tac dung lan kinh anh C Tia tfl ngoai cd budc sdng nhd hon budc tia hdng ngoai va tia Rong-hen D Ca ba loai tia tran deu khong nhin thdy dupe Cau Trong eae ka't luan sau, kdt luan nao sai ndi ve kha nang giao thoa cua cac loai tia ? A Anh sang nhin thdy dupe cd kha nang giao thoa B Tia tfl ngoai cd kha nang giao thoa C Tia hdng ngoai ed kha nang giao thoa D Tia Ron-gen khong cd kha nang giao thoa vi ed budc sdng nhd 125 BAI42 Thtrc hanh : x A c DINH B l / d c SONG A N H SANG I-MUCTl£U Ve kie'n thflc - Thidt kd dupe phuong an thi nghiam budc sdng anh sang bang phuong phap giao thoa anh sang - Xac dinh budc sdng crua anh sang don sac dya vao hian tupng giao thoa ciaa anh sang don sac qua khe I- ang - Quan sat hian tupng giao thoa cua anh sang trdng qua khe I-ang Ve ki n a n g - Ren luyen kl nang thiet ke phucmg an thi nghiem - Ren luyen kl nang su dung cac dung cu thi nghipm dd tao he van giao thoa, ren luyen ki nang phdi hpp viec didu chinh dng quan sat vdi vipc quan sat vin giao thoa - Ren luyen kl nang phdi hpp viae lam viae nhdm - Ren luyan kl nang thu thap sd lieu, xfl li sd lieu II-CHUXNBI Gido vien - Ve hinh 42.2 va 42.3 SGK tran gidy khd AQ - Chuan bj va kidm tra chat lupng eae dung cu d hai phucfng an thi nghiam bai thyc hanh - Can phai tien hanh trudc eac thi nghiem nau bai thyc hanh Hpc sinh - On lai cac kia'n thflc vd khoang van, budc sdng anh sang va budc sdng anh sang bang phuong phap giao thoa 126 ni - THifiT Kfi HOAT D N G DAY HOC Hoat ddng cua hpc sinh Trp g i u p cua giao vi^n Hoat ddng Kidm tra, chuan bi dieu kien xuat phat Dat va'n de HS suy nghl ea nhan tim eau tra ldi - Cho anh sang don sdc cdn budc sdng giao thoa theo thi nghiem Y Ang Xac dinh khoang van i, va cac khoang each D, a Ap dung cdng thflc tinh khoang van de suy budc sdng anh sang cdn HS nhan thflc dupe vdn dd eua bai hpe GV nau cau hdi kiem tra kien thflc cu - Trinh bay nguyan tde budc sdng anh sang bang phuong phap giao thoa Dat vdn de : Hdm ehung ta ap dung phucmg phap nhu vay dd di budc sdng anh sang eua anh sang dd va anh sang xanh Hoat dong Thiet ke' phuong an thi nghiem budc sdng anh sang dd va anh sang xanh HS thao luan theo nhdm, sau dd dai dian nhdm lan bao cao ket qua GV nau cau hdi thiet ke phucfng an thi nghiem - Hay thia't ke phucmg an thi nghiem dd budc sdng cua anh sang dd va anh sang xanh ? - Diing den day tde ndng sang chieu qua mpt khe hep S Dat hai khe hep S,, Sj song song vdi khe S va nhan anh sang chieu tfl khe S Trudc khe S dat mdt kinh Ipc sac de anh sang chieu tdi khe S, va Sj la anh sang don sac Do khoang vdn i va khoang each D gifla man hflng van giao thoa ddn hai khe S,, S2 Tfl tinh budc sdng cdn 127 HS quan sat va tra ldi eac cau hdi - Sfl dung kinh Ipc sdc dd cdm vao kheL - Dat mdt phia sau man M de quan sat van giao thoa qua kinh Iflp (5) " - Trong thi nghiem nay, ta phai djch chuyen man M bang each dich chuyen dng L2 di eac van sang tdi trung khit vdi cac vach ehia sdn tren thude Khi dd, khoang van i = 0,1mm - Cdn phai D - Ta bd kinh Ipc sac L thi hai ngudn sang S, va Sj la hai ngudn sang trdng, dd, van giao thoa thu dupe tran man la he van giao thoa cua hai chum sang trdng HS chu y quan sat va ldng nghe GV gidi thieu thiet bi thi nghiem tran hinh ve 42.2 Yau cdu HS quan sat va tra ldi cdc eau hdi sau de ndrn dupe each tien hanh thi nghiem - Mudn cd anh sang dd dd lam thi nghiam giao thoa phai lam the nao ? - Dat mat d trudc hay sau man M dd quan sat he van giao thoa? - Thyc ta' thi nghiem ta co phai khoang van giao thoa khdng ? Ndu khdng ta phai lam gi ? - Vdy thi nghiam ta cdn phai dai lupng nao ? - Mudn quan sat hian tupng giao thoa cua hai chum sang trdng ta phai lam thd nao? GV gidi thiau phuong an thi nghiem budc sdng anh sang dd bang bp thi nghiam vdi den laze ban ddn -^5mW - Ddi vdi phucmg an thi nghiem ngudi ta dimg den laze ban ddn phat anh sang dd thay cho viae dung den day tde ndng sang va kinh loc sdc nhu phuong an thi nghipm - He thdng den laze, bang chfla bai khe S,, S2, man hflng he van giao thoa dupe gdn tran gia - Can phai khoang D va khoang vdn i bang thude Do khoang van i bang 128 each khoang each cua vah sang hoac van tdi lian tidp, sau dd tinh khoang van i Hoat ddng Phan nhom, nghiem tie'n hanh thi Cac nhdm trudng lan nhan thidt bj thi nghiam vd cho nhdm va nhan mdu bao cao thi nghiem - Sau cac nhdm da tien hanh xong ca hai phuong an thi nghiem thi lau chui, xdp lai gpn gang cae dung cu thi nghiem va ban giao lai cae thia't bj thi nghiem cho GV GV chia ldp cae nhdm thi nghiam, hai nhdm lam theo phucmg an 1, hai nhdm lam theo phuong an Sau lay dupe sd liau, cac nhdm ddi thi nghiem cho dd tia'p tuc lam phucmg an thi nghiem cdn lai - Trong qua trinh HS lam thi nghiem, GV di tdi tflng ban thi nghiem dd djnh hudng giup dd HS HS gap khd khan Hoat ddng Xfl li sd lieu va via't bao cao thi nghiem HS thao luan nhdm, sau dd ca nhan xfl li sd lieu va via't bao cao - Phuang dn I: edn phai tinh: Yau cdu HS xfl li sd lipu va vidt bao cao thi nghiem theo mdu cd san SGK GV yau cdu HS nau each tinh sai sd mdi phuong an thi nghiam va gia trj eua budc sdng anh sang X='-^ D , r f A i Aa AD^ AX = X\ - = - + ^ ^ - ^ Vi a D ) vfli A D ^ ^ " ^ ^ " ^ * " ' " - Phuang dn : cdn phai tinh - _ ^1 + ^ '*' ^ AX — "*^^ TKBG VL#12/2(NC) _1 "^'" GV thu bao cao thi nghiem cua HS sau HS da xfl li sd lieu va viet xong bao cao thi nghiam 129