Cong thufc a n h sang p h a t quang: P S u y r a H = ^ = ^A=^ P„ N ^ ^H.^ N he = n = 0,2.^ 0,26 = Vdy chgn dap an A Cdu 19: K h i n o i ve he M a t Trcfi, p h a t bieu nao sau day s a i ? A Sao choi la t h a n h v i e n cua he M a t Trcfi B Cac h a n h t i n h chuyeii dong quanh M a t Trcf' theo cung mot chieu C H a n h t i n h gan M a t Trcfi n h a t la T h u y t i n h D H a n h t i n h xa M a t Trcfi n h a t la T h i e n Vifc^ng t i n h • Giai T h i e n vLfcfng t i n h k h o n g p h a i la h a n h t i n h xa m a t trcfi n h a t Vdy chon dap an D Cdu 20: Chieu tCf midc r a k h o n g k h i m o t chum t i a sang song song r a t hep (coi nhir m o t t i a sang) gom t h a n h p h a n don sSc: t i m , lam, do, luc, vang T i a 16 dcfn s i c mau luc di la la m a t niTdc (sat v i m a t phan each giufa h a i m o i trifofng) K h o n g ke t i a do'n sac m a u luc, cac t i a 16 ngoai k h o n g k h i la cac t i a dcfn sSc mau D do, vang C t i m , l a m , B do, vang, l a m A l a m , t i m Giai Dieu k i e n de c6 h i e n tiTcfng phan xa toan phan: itxji > igh va anh sang di tCr m o i triTdng c6 bii6c s6ng 16n sang m o i triTcfng c6 bir6c s6ng be hcfn V i cung goc tori it^i = (igh)iuc va sinigh = — nen: n (igh)d6 > - (igh)luc > - (igh)tim Vay t i a va t i a v a n g k h o n g b i phan xa toan p h a n hay n6i each khac t i a va t i a v a n g b i t a n sSc 16 r a ngoai k h o n g k h i Vdy chgn dap an D Cdu 21: Nguyen tac hoat dong cua quang dien t r d dUa vao A h i e n tiicfng quang d i e n B h i e n tucfng p h a t quang cua chat r a n C h i e n ttrgng quang dien ngoai D h i e n tUcfng t a n sac a n h sang 114 • Giai Chi tiet de thi T S D H , C D M o n VSt II Giai Nguyen tac hoat dong cua quang dien t r d diTa vao h i e n t i i d n g quang dien t r o n g Dap an dung Id A Cdu 22: D a t dien ap xoay chieu u = Uocoscot (Uo k h o n g doi va co thay doi diitfc) vao hai dau doan mach gom dien t r d t h u a n R, cuon cam t h u a n CO t i i cam L va t u dien c6 dien dung C mSc n o i t i e p , vdri CR^ < 2L Khi 0) = coi (0 = 0)2 t h i dien ap hieu dung giOfa h a i b a n t u d i e n c6 cung mot gia t r i K h i co = COQ t h i dien ap hieu dung giufa h a i b a n t u dien dat cifc d a i He thufc Hen he giufa coi, CO2 va coo l a : A C0o=-(co^+co^) C COQ = -y/c0|C02 D- C0o-^(co,+co2) vco- COn B co;^ GiSi K h i CO = coi hoac co = C02 ta co: C| c, c, C2 ^1 "-^ ^2 1 (0,/ co,L co,C, co;.R"+co,.L co,L- CO, 2co;L c c =—+ co,C, =co^R'+co;.L'- (co;-co^) L / 9T > w6i R'< = L-(cof-co^) (cof-co2) = L-(co;'-co2) 2L - R ^ 2co?L (1) — 2L _ C M a t khac (Uc)max theo co k h i COQ = • L a y (2) thay vao (1) t a co: Vdy chgn dap COQ = ^(co, , (2) +0)3) an A Giai Chi m de thi TS DH, CD Mon Vat li 115 Cdu 23: K h i electron d quy dao diTng thuT n t h i n a n g liTcfng cua nguyen tijf hidro difcfc xac d i n h bori cong thufc E„ = ^ ^ ( e V ) (vdfi n = 1, 2, 3, ) n K h i electron t r o n g nguy*n tuf hidro chuyen tii quy dao dCrng n = ve quy dao difng n = t h i nguyen tuf phat photon c6 biTdc song \ K h i electron chuyen tiT quy dao dCrng n = ve quy dao diTng n = t h i nguyen tuf phat photon c6 biTdrc song M o i l i e n he giCfa h a i birdrc song \a 1, la: D C 189?., = 0 X , B ? i = 128 X, A = 4\ = 5\ Giai T a c6: X, he = ^ ^ E - E , ^ =- E„ 25 E„ ^ (1) 21 (2) 100 8E„ L a y (1) chia cho (2) t a c6: ^2 800 _ X, 21Eo 189 =^mX2 =800\ 100 Vdy chon dap an C Cdu 24: Neu n o i h a i dau doan mach gom cuon cam thuan L mac noi tiep v6i dien t r d t h u a n R = Q vao hai ciic cua nguon dien mot chieu c6 suat dien dong k h o n g doi dien tror t r o n g r t h i t r o n g mach c6 dong dien k h o n g doi ciforng I D u n g nguon dien de nap dien cho mot t u dien C O dien dung C = 2.10"^F K h i dien t i c h t r e n t u dien dat gia t r i C L T C dai, ngat t u dien k h o i nguon r o i noi t u dien v d i cuon cam thuan L t h a n h mot mach dao dong t h i t r o n g mach c6 dao dong dien tCr tif vdfi chu k i bang 71.10~^s va ctfcfng dong dien ciTc dai bang 81 Gia t r i cua r bang: A I Q B Q C , Q D 0,25Q Giai T a c6: \ E 1=1—-;Qo=cE R +^ ^ r =^ - R = lQ Vdy chgn dap an A 116 Giai Chi fiSt thi T S D H , C O M6n Vat I ... ? i = 128 X, A = 4 = 5 Giai T a c6: X, he = ^ ^ E - E , ^ =- E„ 25 E„ ^ (1) 21 (2) 100 8E„ L a y (1) chia cho (2) t a c6: ^2 800 _ X, 21 Eo 189 =^mX2 =800 100 Vdy chon dap an C Cdu 24 : Neu... co,L- CO, 2co;L c c =—+ co,C, =co^R'+co;.L'- (co;-co^) L / 9T > w6i R'< = L-(cof-co^) (cof-co2) = L-(co;'-co2) 2L - R ^ 2co?L (1) — 2L _ C M a t khac (Uc)max theo co k h i COQ = • L a y (2) thay... thufc Hen he giufa coi, CO2 va coo l a : A C0o=-(co^+co^) C COQ = -y/c0|C 02 D- C0o-^(co,+co2) vco- COn B co;^ GiSi K h i CO = coi hoac co = C 02 ta co: C| c, c, C2 ^1 "-^ ^2 1 (0,/ co,L co,C,