Vật lý 12 tóm tắt lý thuyết và bài tập trắc nghiệm tập 1 (p2)

CHltawe 1: DAD n W CB m O B VJT I t n - TtM TAT Lt THUYfT VA BAl TAP TRAC MHlgM - Ti Cau : v = STT C O S tfAT LY 12 - TOH TAT lY THBYgT VA BAl TAP TRAC WBHlgM - TAP X = A c o s ( l O t ) cm (p = (nt + -» X = sin (nt + ^ ) ^ '^os (^^ Cau : ^) ^ = 40 r a d / s ; ^ = ^ co = = cm; o) = = ^ ^ = 5cm; 6J 71 Cau : CHIfflHB1:BABDtNBCflH8l / 7r\ (p = - - ^ x = 5cos (lot - - j c m ^ r = 1,26 s Xn C a u : t = 0,Xo Cau : ;K:O V - = ^,Vo = cos < ^ , A sin(p > => (p = ^ = 2V3 cm; -4071 sin = -2071 c m / s < 42 43 44 45 46 47 48 49 50 A B B A B B C A A 51 52 53 54 55 56 57 58 59 60 B C a u : T = r J ^ = 0,4s; W^^rnax) = W = ^kA^ =^ A = Scm 41 B C a u : t = -> X = 0; M^tCmax) x = y4,-»At = J = 0,25 C B D B A A D B C C a u : (o = 27r/ = 47r rad/s;A = 20cm; n / n\ (p = + ^ X = 20cos\4nt + - cm C a u : y4 = c m ; w = — = 7r T X = C a u 3 : a = -oi^x -^x = 3cm; x = ^4cos? =» i4 = 2V3 cm/s —; s ' w =—^ A cos cm /l2 = + - - = » |i7| = 107rV3 c m / s Cau : T = ^ 100 ^2 = = 0,314 =20—, s + Oi' C a u : T = 27r - = , s 6> A = 4cm t = 0,^0 = 2cm, VQ > sinq) < C a u : T = 271 — = 0,5 s A: = Cau : = Ao) = ;4 - = 2m/s C a u : o) = C a u : r = ^ = 0,5s cos ( t - f ) c m cj = 4n;A = ^ m = 10VlO^;^2 = C a u 4 : A l = ^ = 1cm;let = lo m s = ioV3 m/s= + Al = c m C a u : ^ = c m =>A = 4cm; A'^ = ^ = ^ , _ = 5cm;(p = + | A: = cos ^47rt + ^ ) = - s i n ( T t ) c m C a u : A = c m , (o = + - > 6) = 27r rad/s x^+^ -> T = I s 57 WAT It« - JtU CIHMRG1:DMB(IIGCI(HQC TAT I Y THBTfT WA BAl TAP THAC •BHICM-TAPI Cau 46: Chieu dai 16 xo ti I5 nghich voi dp cung, cat bat 16 xo mpt nura =^ cung tSng gdp doi => chu ki giam ^/2 Cau 47: r' - r = 27r (Jf - Jf) = 0,083s Cau 48: r = = o,314s; m = ^ = = 0,3125k^ = 312,5flf =^A = V m a x J| = 3cm Cau 49: Vmax = Ao) = Cau50: r = i50 = , » s f c = ma>2 = m ( ^ ) = 160N/m ^ \ / C a u :Ti^ = P 61 C 71 C TAT I t THBYfT VA BAI TAP TRAC I R H I | M - TjP 62 A 72 63 D 64 C 74 A B D 73 65 66 A 76 C B 75 B CHa0N61:BABB9NGCtfl 67 D 77 C = + r| -» T = I Cau 55: At = = I s • •• B \ -4 -2 +4 = max =^ \x\ ^-^ A = 6cm; Wt = 10 rad/s -> = 0,628 s Cau63:a>= /^=107r — ; yjm A^=x^ + -6 s Cau 58: At = - = 0,5 s x = 3cm - +6 ACTTI.VQ T A =>At = - - * s = — = 2cm Cau 60: x = 2cm; v /3cm D.2^/3cm Cau 21: Mgt sgi day dan hoi cang ngang Lam cho dau A cua day dao dgng theo phuong thing dung voi bien l,5em va chu ky 0,5s Luc t = 0, A c6 li cue dai duong Song truyen di dgc theo day voi toe dg 3m/s Coi bien song khong d6i Li dg cua dilm M each A mgt doan 2m tai thai dilm t= 1,25s la: A - 0.75cm B + 0,75cm C -1,5em D + 1,5em Cau 22: Mgt song ea hgc truyen tir O theo phuong x Dao dgng tai diem O CO dang: UQ = 3eos(0,57rt) (cm) Biet li dg ciia dao dgng t^i M a thai dilm t la em Hay xac dinh li dg cua diem M sau thai diem s A 3em B.-3cm C 6cm D - cm Cau 15: Mot song ca hoc phat tir mot ngu6n O Ian truygn tren mat nuoc van toe 2m/s Ngudi ta thay hai diem M, N gin nhdt tren mat nuoc nam tren eung duong thing qua O vd each 40em luon dao dong ngugc pha Tan so song la: A.0,4Hz B l,5Hz C 2Hz D 2,5Hz Cau 16: Mgt sgi day dan hoi, manh, rat dai, c6 dau O dao dong dieu hoa voi tan so f theo phuong vuong goc voi sod day Song tao Ian truySn tren day voi toe Idiong doi v = 5m/s De diem M each O mpt khoang bang cm luon dao dong eung pha voi O thi tan s6 dao dpng nhan gia tri nao eac gia tri sau? A.40HZ B.60HZ C 50Hz D 30Hz Cau 17: Mot day dan hoi rit dai c6 dau A dao dong voi tan s6 f theo I' phuong vuong goe voi sgi day Bien dao dong la a, van t6e truyen song Cau 23: Hai diem M, N eung nim tren mgt phuong truyen song each tren day la 4m/s Xet diSm M tren day va each A mgt doan 14cm, nguai U X/3 Tai thai diSm ti eo UM = +3cm va UN = -3cm Tinh bien dg song A? thay M luon dao dong nguge pha voi A Bilt tan so f c6 gia tri khoang A.A = 2V3cm B.A^SVScm tir 98Hz den 102Hz Buoe song cua song eo gia tri la ||, C A = cm D A = V6 em A 4em B 6cm C 8cm D 5cm Cau 24: Song ca c6 tin s6 40 Hz Ian truyen mgt moi truofng voi van Cau 18: Dau O cua mgt sgi day dan hoi dao dgng voi phuong trinli t6c m/s Hai dilm tren mgt phuong truyen song each nguon song nhiJng u = 2cos(27it) (cm) tao mgt song ngang tren day c6 van t6c v = 20 cm/s doan Ian lugt 10 cm va 12,5 em, dao dgng Mgt diem M tren day each O mgt khoang 2,5 cm dao dgng voi phuong trinh: A vuong pha B nguge pha CHI/dNG 2: SONG Ml • WAT li n - I J H TAT lY TWTfT WA lAl TAP TRAC MGHlgM-TAPI G I A O T H O A SONG Cau 25: Chpn cau dung nhat: Hai nguon song tren mSt nuac thoa dieu kien ket hop klii MAT LY 1? - TtM TAT lY THUYfT VA BAI TAP TBAC HGHIgM - TAP CHIfdNB 2: SdNG Cd ngu6n tao khong d6i qua trinh song truygn Trong khoang giua A va B CO giao thoa song hai nguon tren gay Phan t i i vat chSt tai trung dikm eua doan A B dao dpng v a i bien dp bang A B.a/2 , C.a D.2a A Cung tan so va eo hieu so pha khong doi B Cung tan so va eung pha C Cung thn s6 va nguge pha D Cung tan so va eung bien Cau 26: (De t h i dai hoc nam 2007) ^ e khao sat giao thoa song ea, nguai ta bo tri tren mat nuac nam ngang hai nguon ket hgrp Si va S2 Hai nguon dao dong dieu hoa theo phuong thang dung, ciing pha X e m bien song khong lhay d6i qua trinh truyen song Cac dikm thuoc mat nuac va nam tren duong trung true eua doan S1S2 se A dao dong v a i bien bang nua bien dp cue dai B dao dong v a i bien c\rc tieu Cau 30: Hai nguon kk hgp A va B giong tren mat thoang chdt long dao dpng v a i tan so 8Hz va bien dp a = 1mm Bo qua s\ mk mat nang lugng k h i truy§n song, van toe truyen song tren mat thoang la 12 cm/s Digm M nam tren mat thoang each A va B nhimg khoang AM=17,0cm, B M = 16,25cm dao dpng v a i bien dp A 0cm B 2em Clem D.l,5cm Cau 31: (De thi cao dSng nam 2009) CJ mat nuac c6 hai nguon song dao dpng theo phuong vuong goc v a i mat nuac, c6 cung phuong trinh u = Acos(cot) Trong mien gap cua hai song, nhijng diem ma a cac phan tijr nuac dao dpng v a i bien dp c\rc dai sS c6 hi?u duong di eiia song tir hai nguon den bang C dao dpng v a i bien cue dai A mot so le Ian nua buac song D khong dao dong B mot s6 nguyen Ian buac song Cau 27: Trong hien tugng giao thoa eua hai song phat t u hai ngu6n dao dong nguge pha,vai k la so nguyen va A la buac song, nhung diem moi truong truyen song dao dong v a i bien cue tieu k h i hieu duong di cua hai song thoa A (2k + l ) - B (2k + l)> C ( k + - ) - D.kX C mpt so nguyen Ian nua buac song, D mpt so le Ian buac song, Cau 32: Tai hai d i l m A va B tren mat nuac c6 ngu6n song nguge pha, cung bien dp a, buac song la 10cm, Coi bien dp khong doi truyen di Diem M each A 25cm, each B 35cm sS dao dpng v a i bien dp bang A a Cau 28: K y hieu X la buac song, di-d2 la hi?u khoang cdch tir diem M d i n cac ngu6n song ket hgp Si va S2 mgt moi truong d6ng tinh k = 0, ± 1; ± 2, Diem M se luon luon dao dong v a i bien cue dai neu A di - d2 = (2k + 1) X,^ neu ngu6n dao dpng nguge pha D di - d2 = (k + 0,5) X , neu hai nguon dao dpng vuong pha pha Cau 29: Tai hai diem A va B mot moi truong truyen song c6 hai nguon song ket hgp, dao dpng eung phuong v a i phuomg trinh ihn lugt la u^ = acoscot va Ug = acos(cot +7t) Biet van toe va bien dp song moi C 1,5a D Cau 33: Trong mpt t h i nghiem ve giao thoa song tren mat nuac, nguon ket hop Si va S2 dao dpng cung 15Hz Van t6c truyen song tren m | t nuac la 30cm/s V a i diem M eo nhung khoang di va d2 nao duoi day se dao dpng vai bien dp cue dai? A di = 25cm va d2 = 20cm, B di - d2 = k X , neu nguon dao dpng cimg pha C di - d2 = X-^ neu nguon dao dpng nguge pha B.2a l^PI' B di = 25cm va d2 = 21cm C di = 25cm va d2 = 22cm, D di = 20em va d2 = 25cm, Cau 34: Th\rc hi?n giao thoa song ca hpc vol ngu6n ket hgp Si va S2 dao dong cimg pha va cung bien dp 1cm, buac song A ^ 20em Hoi nguon M each ngu6n Si va S2 cac khoang 50cm va 100cm se dao dpng vai bien dp A B V2cm C cm D 2cm 89 CHIfdHG Z: 50IIB Cd VAT lY « - TlJM TAT i t THBYgT Mk BAI TjP TRAC MHlgH - TAP Cau 35: (De thi dai hoc nam 2009) Dieu ki?n dk hai song ca gap nhau, giao thoa dugc vai la hai song phai xuat phat tir hai ngu6n dao dong A cung bien va c6 hieu s6 pha khong doi theo thai gian B cung tan so, cung phuong C CO cung pha ban dau va cung bien D cung tan so, cung phuang va c6 hi?u so pha khong doi theo thai gian Cau 36: De hai song ket hgrp giao thoa cung pha tri?t tieu thi chung phai c6: A Cung bien do, hieu duong di bSng mot so nguyen Ian nua buac song VAT LY 12 - TdM TAT lY THPYgT WA BAI TAP THAC WSHIgM - TAP Cau 40: (Cao ding 2007) Tren mat nuac n i m ngang, tai diem Si va S2 each 8,2cm, nguoi ta dat nguon song ca ket hgp, dao dgng dieu hoa theo phuang thing dung c6 tan so 15Hz va luon dao dong d6ng pha Biet van t6c truySn song tren mat nuoc la 30cm/s, coi bien song khong d6i truySn di S6 diem dao dgng voi bien dp c\rc dai tren doan S1S2 la: A D Hi$u duong di bSng mpt so ban nguyen Ian buac song Cau 37: Phat bieu nao sau day la khong dung? A Khi xay hien tugmg giao thoa song tren mat chat long, ton tai cac diem dao dong vai bien dp cue dai B Khi xay hien tugng giao thoa song tren mat chat long, ton tai cac dilm khong dao dong C Khi xay hien tucmg giao thoa song tren mat chat long, cac diem khong dao dong tao cac van cue tieu D Khi xay hi^n thugng giao thoa song tren mat chat long, cac diem dao dong manh tao cac duong thing cue dai Cau 38: Trong hi?n tugntig giao thoa song tren mat nuac, khoang each giiJa hai cue dai lien tiep nam tren duong noi hai tarn song bing B 11 C D Cau 41: Dung mot am thoa tao tai hai diem Si, S2 tren mat nuoc hai ngu6n song cung bien dp, ngu-gc pha Khoang each giiia nguon Si, S2 la 16,4cm K i t qua tao nhilng ggn song dang hyperbol, khoang each ngin nhk giCra hai ggn loi lien tiep la 2cm So ggn loi va lom xuit hien giiia hai dilm S1S2 la B Cung bien va hieu duong di bang mot so le Ian nira buac song C Hieu duong di bing mot so nguyen ihn buac song CHlAfNG Z: SdllG I A.8va9 B.9val0 C v a l D 8va7 Cau 42: mat nuoc c6 hai nguon song co A va B each 15 cm, dao dong dieu hoa ciing tan so, cung pha theo phuong vuong goc vai mat nuoc Diem M nam tren AB, each trung dikm O la cm, la diem gin O nhat luon dao dong voi bien dp c\rc dai Tren duong tron tam O, duong kinh 10cm, nim mat nuoc c6 so diem luon dao dong voi bien dp cue dai la A 18 B 16 C.20 D 17 Cau 43: Trong thi nghi^m giao thoa song tren mat nuoc, hai ngu6n AB each 18cm dao dong cung pha Diem M tren AB gan trung diem I cua AB nhat, each I la 2cm luon dao dong c\rc dai So diem dao dpng cue dai tren duong elfp thupc mat nuoc nhan A, B lam tieu diem la A 20 B 18 C.28 D 14 Cau 44: Tai hai diem tren mat nuoc, c6 hai ngu6n phat song A va B c6 A Bang hai Ian buoc song phuong trinh u=acos(40Tct) (cm), van t6c truyln song la 50 cm/s, A va B B Bang mot buoc song each 11cm Gpi M la diem tren mat nuoc c6 M A =10 cm va MB=5 C Bang mpt nua buoc song jliCm D Bang mot phan tu buoc song Cau 39: Mpt sgd day cao su cang thing n i m ngang c6 dhu A noi vai mot ban rung c6 tan so f = 0,5Hz Sau 2s dao dong truyen di dugc 10m, hoi tai diem M tren day each A mgt doan 5m c6 trang thai dao dpng so voi A la: A Ngugc pha B Cung pha C L?chpha — rad D Lfchpha — rad So diem dao dpng c\rc dai tren d o ^ A M la A B C D Cau 45: Tai hai dilm A, B tren mat nuoc c6 hai ngubn dao dpng cung pha va cung tan so f = 12Hz Tai diem M each cac nguon A, B nhung doan di = 18cm, d2 = 24cm song c6 bien dp c\rc dai Giua M va duong trung true cua AB CO hai duong van dao dpng voi bien dp c\rc d^i Van t6c truySn song tren mat nude bing bao nhieu? A.24cm/s B.26cm/s C.28cmys D.20cm/s 9ll CHIiQNB t SONG Cd VAT I t « - T J H TAT lY T M g VA BAl TAP TRAC II6HI£III - TAP H YT Cau 46: Tai hai diSm A va B tren mSt nuac c6 hai ngu6n ket hop cung dao dong vori phuong trinh: u = acos(100;rt) (cm) Van toe tniyen song tren mat nuac la V = 40 cm/s Xet dilm M tren mat nuae eo AM = cm va BM = cm Hai dao dong tai M hai song tir A va B truyen den la hai dao dong A cung pha B ngugrc pha C vuongpha D lech pha 2rr/3 Cau 47: mat ehdt long c6 hai nguon song A, B each 18 cm, dao dong theo phuorng thing dung vai phuong trinh la = U B =acos(507rt) (vai t tinh bang s) T6c truySn song a mat chat long la 50 em/s Goi O la trung diem eua AB, diem M a mat chk long nam tren duang trung true cua AB va gan O nhdt cho phSn tu chat long tai M dao dong cung pha vai phan tu chat long tai O Khoang each MO la A cm B 10 cm C l^l em D 2710 cm • SONGDlTNG Cau 48: Chpn ket luan sai noi ve s\ phan xa cua song A Song phan xa luon luon c6 cung van t6c truyen vai song tai nhung ngugre huomg B Song phan xa luon luon cung pha vai song tai C Song phan xa c6 cung tin so vai song tai D Sir phan xa a dau c6 dinh lam doi ddu phuang trinh song Cau 49: Song dung duac hinh bai: A Sir giao thoa cua hai song ket hgrp B S\ giao thoa cua mot song tai va mpt song phan xa cua no cung truyen theo mot phuong C Sir t6ng hgrp khong gian ciia hai hay nhieu s6ng ket hap D Sir t6ng hgrp cua hai song toi va song phan truyen khac phucmg Cau 50: Chgn cau dung Khi c6 song dung tren day dan h6i thi A tat ca cac dikm tren day deu dimg lai khong dao dong B nguon phat song ngimg dao dgng cac diem tren day van dao dgng C tren day c6 cac diem dao dgng manh xen ke voi cac diem dung yen D tren day chi song phdn x?, s6ng tai bj trigt tieu WAT LY n - Tiw TAT li mi€j vA BAI TAP TBAC IIEHIEM - IAP I CHKIAIG 2: SiNG Cd Cau 51: Mot day dan dai 60cm phat mot am c6 tin s6 lOHz Quan sat song dimg tren day nguai ta thay c6 nut g6m ca nut a dau day.Van t6c truyen tren day la: A 4cm/s B.40cm/s C.4m/s D.6m/s Cau 52: Mgt sgd day dan hoi dai 50 cm c6 hai dau c6 dinh, dao dong tri vai tan so f = Hz, tren day c6 song dimg on dinh vai byng song Van toe truyen song tren day bang A 0,4 m/s B m/s C 0,5 m/s D m/s Cau 53: (De t h i cao dSng nam 2009) Tren mgt sgd day dan h6i dai 1,2 m, hai dau c6 dinh, dang c6 song dung Bik song truyen tren day c6 tan so lOOHz va toe dg 80m/s So b\mg song tren day la: A B C.4 D Cau 54: Day AB cang nam ngang dai 2m, hai dau A va B c6 dinh, tao mot song dung tren day vai tin so 50Hz, tren doan AB thay c6 nut song Van toe truyen song tren day la: A lOOm/s B 50m/s C.25m/s D 12,5m/s Cau 55: Mgt day AB dai 100cm c6 diu B c6 dinh Tai dau A th\rc hien mot dao dgng dieu hoa c6 tan s6 f = 40Hz V$n toe truyen song tren day la v = 20m/s So diem nut, s6 diem b\mg tren day la bao nhieu? A nut, bving C nut, b\ing B nut, byng D nut, b\mg Cau 56: Mgt sgi day dan hoi AB hai dau c6 djnh Khi day rung voi tan s6 f thl tren day c6 bo song Khi tan so tang them lOHz thi tren day c6 bo song, v§n tpc truyen song tren day la lOm/s Chieu dai va tan s6 rung cua day la: A l = 50cm,f=40Hz C = 5cm, f = 50Hz B l = 40cm, f = 50Hz D = 50cm, f = 50Hz Cau 57: V^n t6c truyen song tren mgt sgd day la 40m/s.Hai dau day c6 dinh Khi tin so song tren day 200Hz, tren day hmh song dung vai 10 bvmg song.Tin so nao cho duod day ciing tao song dimg tren day: A.90HZ B.70HZ C.60Hz D llOHz I CHlflMG t SdNG Cd Hi I t 12 - Tim TAT LY THUYfr v BAI TAP TBAC H G H I £ M - T A P I A Cau 58: Mot day AB dai 1,80m cSng thing nim ngang, dau B c6 djnh, dau A gin vao mpt ban rung tan so lOOHz Khi ban rung boat dpng, nguoi ta thay tren day c6 song dimg g6m bo song, voi A xem nhu mpt nut Tfnh buac song va van toe truyen song tren day AB A.X = 0,60m; v = 30m/s B X = 0,30m; v = 60m/s C A, = 0,60m; v = 60m/s Dl=l ,20m; v = 120m/s Cau 59: Mpt sgi day manh AB dai 1,2m khong gian, dau B c6 dinh, diu A dao dong voi f = lOOHz va xem nhu mot nut, t6c truy6n song tren day la 40m/s, bien dp dao dong la 1,5cm S6 b\mg va be rpng cua mpt biing song la A bung, 3cm B 6b\mg, 3cm C 7bung, 1,5cm D b\ing, 6cm Cau 60: Quan sat song dimg tren sgi day AB, dau A dao dpng diSu hoa theo phuomg vuong goc voi soi day (coi A la nut) Voi dau B t\ va tan so dao dong cua dhu A la 22 Hz thi tren day c6 nut NIU dau B c6 dinh va coi toe truyen song tren day nhu cu, de van c6 nut thi tan s6 dao dong cua diu A phai bang A 25 Hz B 18Hz C.20Hz D 23 Hz Cau 61: S6ng dimg tren mpt sgi day dan hoi c6 bieu thuc: M = 2cos(—)cos(20;r/+^„)(c/?j) Trong u la U dg tai thai diem t cua mgt phan tu M tren day m^ vi tri can bang cua no each goc O mgt doan la x (X b3ng cm; t bSng s) Van t6c truyen song tren day A 80 cm/s B 40 cm/s C 160 cm/s D 100 cm/s Cau 62: Mgt sgi day AB = 60cm voi dau B c6 djnh Ddu A dao dgng vai tan so 50Hz thi tren day c6 12 b6 song nguyen va A xem nhu mgt nut song Neu A la nut song thu nhat, diem N each A mgt d o ^ 20cm la A nut s6ng thu B bung s6ng thu C nut song thii D b\mg song thu Cau 63: (De thi dai hpc nSni 2011) Mgt sgi day dan hoi cang ngang, dang CO song dimg 6n dinh Tren day, A la m^t diem niit, B la mgt diem b\mg gan A nhat, C la trung diem ciia AB, vai AB = 10 cm Biet khoang thai gian ngSn nhdt giOa hai Ian m^ li dg dao dgng cua phan tijr tai B bing bien dao dgng cua phSn tu t^ Cl^ 0,2 s T6C dg truyen s6ng tren day la A 0,25 m/s B m/s C 0,5 m/s D m/s If AT LY 1Z - TiM TAT lY THBYgl VA BAI TAP TBAC BBHlgM - TAP CHI/tfNG Z: StNG Gd • SONG AM Cau 64: Dilu nao sau day la sai noi ve song am? A Song am la song ca hgc dgc truyen dugc moi trucmg vat chat ke ca chan khong B Song am c6 tan s6 nim khoang tir 16Hz den 20.000Hz C Song am khong truyen dugfc chan khong D Van toe truyen am ph\ thugc nhift dg , Cau 65: Chgn cau dung Am sSc 1^ dSc tinh sinh ly cua am dugc hinh dira tren dac tinh vat ly cua am la: A Bien dg B Tan so C Nang lugng am D D6 thj dao dgng am Cau 66: Chgn cau dung Dg cao cua am phu thugc vao: A Bien dg B Tan s6 C Nang lugfng am D Van t6c truySn am Cau 67: Chgn cau dung Dg to cua am ph\ thugc vao: A Tan so va bien dg am B Tan s6 am va miic cuang dg am C Buac s6ng va nang lugmg am D V$n toe truyen am Cau 68: Am thanli truyen nhanh nhat moi truang nao sau day? A Khong B.Nuac C Sat D.Khihidro Cau 69: Phat hiku nho sau day 1^ dung nhSt ? A Am CO cuang dg Ian thi tai ta c6 cam giac am "to" B Am c6 cuang dg nh6 thi tai ta c6 cam giac am "be" C Am CO tan s6 Ian thi tai ta c6 c ^ gidc am "to" D Am "to" hay "nh6" ph\ thugc vko muc cuang dg am va tan so am Cau 70: (De thi d^i hgc nam 2008) Mgt la thep mong, mgt dkn c6 dinh, l^i dugc kich thich de dao dgng v6i chu ki khong doi va bang 0,08 s Ani Id thep phat Ik A Sieuam B.Haam * C Nhac am D Am ma tai nguai nghe dugc C K N 2: SdNG C Hd G O «AT LV 12 - T6M TAT LY THUYft «A BAl T A P TRAC IISHigM - T A P Cau 71: (De thi cao ding nhm 2009) Khi song am truySn tir moi truomg khong vao moi truong nuac thi A chu ki cua no tSng B tan so cua no khong thay doi C buoc song cua no giam D buoc song cua no khong thay d6i Cau 72: Song ca hpc Ian truyen khong khi cuong du lom, tai ta CO the cam th\ duac song ca hoc nao sau day: A Song CO tan s6 lOHz B Song c6 tan s6 30kHz C Song CO chu ky // s D Song c6 chu ky 2ms Cau 73: (De thi cao ding nSm 2010) Khi noi ve song am, phat bieu nao sau day la sai? A d Cling mpt nhi?t dp, toe dp truySn song am khong nho hon t6c dp truyen song am nuae B Song am truyen dupe cac moi truong rin, long va khi, C Song am khong la song dpc D Song am khong la song ngang Cau 74: Mpt nguoi dung truae each ngu6n am S mpt doan d Nguon phat song cau Khi nguoi di lai gin ngu6n am 50m thi thay cucmg dp am tang len gdp doi Khoang each d la: A «222m B «22,5m C « 29,3m D «171m Cau 75: Mpt nguon diSm O phat song am c6 cong suat khong doi moi moi truomg truyen am dang huong va khong hap thu am Hai diem A, F each nguon am Ian lupt la ri va Biet cuong dp am tai A gap Ian cuon; dp am tai B Ti s6 so vai ri la: A B.2 C 1/2 D.1/4 Cau 76: d khoang each di = 1000m tnrac mpt ehigc loa, miic cuong d am la Li= lOdB Tinh cucmg dp am I2 tai diem nam each loa mpt khoang da = 10m Bik song loa phat Ian toa khong gian dual dang soir eiu Cho hik cuong dp am chuan la IQ = 10"'^wW A.70W/m2 B 10-'W/m2 C lO'^W/m^ D lO'^W/ml tf AT Lt 12 - Tim TAT LY iHcygT vA BAI T ^ P TBAC wemgH - T A P CHIftfNG 2: SiNG CB Cau 77: Nguon am S phat mot am c6 cong suit P khong doi, truySn ding huong \h mpi phuomg Tai dilm A each S mpt doan rA = Im, muc cuong dp am la 70dB Gia su moi truong khong hap thvi am Mure cuong dp am tai diSm B each nguon mpt doan TB = lOm la: A 30dB B 90dB C 50dB D 60dB Cau 78: Mue cuong dp am tai hai diSm A,B Ian luprt la: 30 dB va 20 dB Suy lien he giiia cucmg dp am tai A va tai B la: A IA = IB/5 B IA = 5IB C IA = IBVIO D IA=10IB Cau 79: Khi song am truyen tir moi truong khong v^o m6i truong nuoc thi A chu ki cua no tSng B tan so cua no khong thay d6i C buoe song cua no giam D bu6e s6ng cua no khong thay doi Cau 80: Khi noi v^ song am, phdt bilu nao sau day la sai? A O cimg mpt nhi?t dp, toe dp truyen song am khong nho horn t6e dp truySn s6ng am nuoc B Song am truyen dupe cac moi truong rSn, long va C Song am khong la song doe D Song am khong la song ngang 97 CHinrNG 2: SfiNG C0 MAT It 1Z - TlJM TAT LY THBYfT VA BAl TAP TRAC I»6HI€M-TAP1 DAP AN CHirONG II C A B B C 10 A Cau 5: / = I = ^ = 50Hz I r = 1,6s; v = ^ = ^ = l,25m/s Cau 8: / = 120//z; 4A = 0,5 A = 0,125m; v = A/ = 0,125.120 = 15m/s Cau 9: ^ = ^ = ^ = 4,4 -> tang 4,4 Wn Ai 330 Vi Cau 10:r = ^ = i^ = 0,ls;^ = -^ = -^ = 20 w 2071 ' ' A T - 0,1 BM tap 2; Qu^ song4- 3$ pha - phirong trinh truyen s6ng trinh truyen l^ch 10 Cau B^p dn D A B A B B C A c Cau 11 12 13 14 15 D^p ^n C C B C D - V 360 „_ ^«"2:A = - = - = 0,8m; Cau 3: A(p = 2Ttx A s d n ^ t X - Bai tap 1: Dinh nghta song cor Can Dap an C B B B A CHI/lfNG2: SdNGCd VAT LY 12 - TIJM TAT LY THUYET VA B A I TAP TRAC HEHIgM - TAP 7: A(p 2nx = — ,n , , 2nfx = ^ - + fcjT = — ^ =^ , k = 1250//z 2fx X = — — - Vi22 A = 16cm A £t 2nfx 2nx n + kin = Cau 8: ^(p = V Vi 0,7 < v < kG2 nenl,5 v = 80cm/s k=tl-l Cau9:uM = c o s [ r ( ^ - g = Cau 10: ^ = ^ A = 3m; v = A/ = A ^ = 0,5m/s Cau 11: ^ = 0,027r:c => A = 100cm 2nx Cau 12: ^ = 0,02;!^: A = 100cm; v = A/ = A2n = 200cm/s — Cau 13: A = = ^ = 5cm; x = 33,5 - 31 = 2,5cm; J Inx80 In 2,5 =n Cau 14: A = vT = = ^ = 9,6cm; (^ 2nx\ n\ 2l UM = 5cos\5nt - — j = 5cos[5nt j(cm) Cau 15: X = vT = v—= - = 20m; UM = 2cos T T t - n 2nxj = cos(7rt) (cni) 5o+- CHI/dNG Z: ^dNG Cd VAT LY I Z - T f i M T A T LY THUYfT VA BAI TAP TRAC M H l g M - T A P l Bai tap 3; Giao thoa song yAT LY IZ - 10 Dap an B C A A A D B B A A Cau 11 12 13 14 15 Dap an D C C B A Cau 4: A = [ i ( ^ ^ ) ] | - di Buac song: X = vT = v— = SO^= ^ cj son So cue dai: = 2a|cos Xet: ^ ' ^ (6.2 - d i \ ] | = 2.201 c o s [71 lOCD CA-CB 8V2-8 1,5 A = 2,2 C ndm giua cue dai bgc va So cue dai tren doan CD: 2.2 + = (ke ca cue dai bae 0) ^ = v — = — = 16cm; A = a | c o s [% ^X -5,5 cd 10 gid tri = 2a ~ " Cau 5: A = Cau 13: Hai nguon dao dong ngugc pha -SiS2 = Cau 15: Hai nguon dao dpng nguae pha; 2n In X = vT = v—=30-—= 1,5cm S6 cue dai tren doan AB: Cau 6: - = 4mm = ^ A = 8mm; / 1\ -5iS2 -13,8 cd 26 gid trifc->26Cf) 17 = A / = 8.100 = 800mm/s = 80cm/5 Cau 7: 11 ^ = 22cm => A = 4cm; v = Xf = 4.20 = 80cm/s So cue dai tren doan BO (O la trung diem eua AB): y = 13 Cau 8: - = 1,5cm A = 3cm; Xet: v = Xf = 3.40 = 120cm/s = l,2m/s Cau 9: d2 - d i = 3A A= •5 MB-MA 20V2-2O 1,5 A = 5,52 —» M ndm giica CD bgc 6vd7 S6 cue dai tu M den duong trung true cua AB: S6 cue dai tren doan MB: + 13 = 19 = 1,5cm; i ; = A / = 1,5.20 = 30cm/s Bai tap 4: Cau 10: d2 - d i = 4A =» A = = 1cm; Cau Cau 11: A = = J = 2cm; -S^S2 - , cd gid trf k 10 A C D C D A D C D c 11 12 13 14 15 Dap an 15 Cau S^Sz Dap an V = A / = 1.20 = 20cm/s A D C A D 9CD 101 CHirdNG 2: StNG Cd VAT LY T2-TliMTAT ij THBTgT VA BAl TAP TBAC W Hg S lM TAP Cau 1: Vat can c6 dinh => song phan xa ngugc pha (ngugc diu) vai song tai vat can: U2 = acos (2nft + n) Cau 2: Song phan xa tai B: = -acos(2nft) Song phan xa tir B truyen den A: = -acos(2nft - ^) Cau 5: ^ = 0,2 V = r = 0,4s; ^ = 10cm A = 20cm; = 50 cm/s >T = >- = — nv nv Cau 8: bwn^ sdn^ -»i = ^ A = 0,5m; i? = A/ = lOm/s Cau 9: 4fown^son^ = 4.^ -> A = 30 cm; t; = A/ = 15m/s Cau 10: fcwn^ sdn^- / = 6.^ -> A = 0,6 m; i? = A/ = 60m/5 Cau 11:4 nut bung song A T / = - - * A = 0,8 m ; - = 0,055 => = 0,1s 1; VAT 1Y 12 - TiM TAT Bai tap 5: Cau Dap an Cau Dap an lY THUYfT VA BAl TAP TBAC N G H I I M - C A C 11 12 13 c D A TAP CHirOilG 2: SANG CI D C D 14 15 A C C Cau 8: L = 2B = 20d5 = 10 I g - -> / = B 10 D IO^IQ y,2 Cau 9: L = 9B = 90dB = 10 Igf / = IO^/Q = 0,001 W/m '0 Cau 10: L2 - Z-i = 20dB 10 Ig^ = 20 => /z = lOO/i Cau 11: /, = 1000/1 = » L2 - ^1 = 10 Ig^ = 30dB '1 Cau 12: - Cau 13: - Cau 14: - LB = AM = Cau 12: A = ^ = ^ = 0,5m; ^ = -> 4fcwn^,5 nwt 10 I g ^ => 90 - 70 = 10 I g ^ => ^ = 100 = 10 I g ^ =» 80 - 40 = 10 I g ^ => ^ = 10000 LB 40 = i = m/s = 10 Igy^ = 10 Ig ( ^ ) = 100 d^ + dg 101 'd 26dB Cau 13: A = - = 1cm; j ^ = M la nut song thu f C '0 Cau 6:1 song ->/ = l.^ = ^ = » / = J Cau 7: i = n - = n i •/ ^2 Cau 14: A = ^ = 0,25m; / = (5 + i ) ^ = 62,5cm; bo song niit song Cau 15: / = = ^ = ^ / = 63//z M C l l G Z: SANG HTM CK V*T lY 12 - TIJM T A T lY THBYfT V A BAl T A P T H A C H G M l g M - T A P I Cau 15: L2 - = 10 \g'f = 10 Ig = 2,24 di - (^f ' ^ V j T lY 12 - TiM TAT LY THBYfT VA BAl TAP T R A C IGHieM - TAP C a u 14: u = cos (4nt - O.Snx - ^)] ( c m ) => = 20 Ig (Ji) / 27rx\ «^ u = acos f cot A / d i = 112m A = m ; / = 4//z -> v = A/ = 8m/s d2 62 C a u 15: - = c m A = 80cm = , m ; / = - = Cau hoi t r a c nghiem tong hoD 10 Dap an B D D C C B A A A A Cau 11 12 13 14 15 16 17 18 19 20 Dap an B B A A D C A B D A Cau 7: = 18s = » T = 2s,X = 2m,v = ^= ^ A cos I 2nt \ / = = 3s => Vthep - f) « 27rr 27rx\ = cos = T ^'^4 T cm a = 5cm T 5294 m/s w = acos (a>t - C a u 20; U M = ^ ) acos(-^ j '2717 c m = acos C a u 12: u = 2cos(20:c - 0 t ) = 2cos(2000t - 20:c) 2713^ a = 4cm 2nx\ Cau C a u 13: u = cos(47rt - 0,0027r;c) u = acos ( w t - ^ ) 22 23 24 25 26 27 28 29 30 B B A B A C D C A A Cau H z -> t; = A/ = lOOm/s 21 Dap an 1000 T T = -> A = c m /2n n 2nx\ a c o s ( - t - - - — j c m = acos A = 50cm = w 60cm/s C a u 9: V = ^ = j ; A = 177 = m ^ = — - - C a u 19 t = 0,u = 0,v > -> uo = a c o s ( ^ t - f ) UM = 2,93 < fc < 3,07 -> Im/s = 0,75s, 3A = 135cm C a u 1 : u = 8cos27r I = fc J C a u 17: Aa? = - — = — - = n + k2n => U M C a u 10: fc^/ V o i fc la s6 nguyen, ta chon / = SOHz, k h i Cau => A = c m ; v = ^ = 2,5Hz A C a u 16: Acp = / c r d = fcA = C a u 8: T = CHIflhlG2:Slill&Cir 31 32 33 34 35 36 37 38 39 40 Dap an B D B A D D D C A A -> A = 100cm 105 CHirifNG V A T LY I Z - Z: S d N G C d VAT lY iz - TOM TAT LY THUY^T VA B A I TAP T B A C N B H I E M - T A P I Cau 21: t = 0,u = + a u = 1,5 cos(47rt) cm ( 2nx\ A = vr = 1,5 m -> = 1,5 cos 147rt - — j / 87r\ = l,5cos (47rt - — j cm t = 1,25s -* U M = +0,75cm Cau 22: Li dp song M tai thai dilm t: / 2nx\ UM = cos (0,57rt - — j = 3cm Li dp song a M tai thai diem t + 6s: / 2nx\ U M = 3cos\O.Sn(^t + 6) - — j / 2nx \ = cos 0,57rt r- +3n = - 3cm Cau 23: Do lech pha giila hai diem M va N: = ^ = ^ Chgn t = luc U M = +3cm va ^ la pha ban dhi, ta c6 acos^ = +3cm va acos(^ + A(p) = - c m Giai he hai phuang trinh tren ta dugc: a = 2V3cm Cau 24: A = p = 5cm; d = 12,5 - 10 = 2,5cm 2nd A(p = —7— = TT nguac pha Cau 30: Hai nguon dao dpng cimg pha BM) A = V7 = l,5cmM = 2a n{AM -— — = 0cm / A Cau 32: Hai ngu6n dao dgng nguac pha: MB-MB = 10cm = A -> Amin = Cau 33: Hai nguon dao dong ciing pha: X = j = 2cm Amax di - =fc.2 TOM TAT LY T H U Y ^ T V A BAI T A P T B A C HGHIgM - TAP CHI/dNGZrSdNGC Cau 34: Hai ngu6n dao dong cung pha: 2a cos A= 7r(M52 - M5i) = 0cm Cau39:17 = ^ = 5m/s,A = j= 10m,A(p = ^ = TT -* ngugcpha Cau 40: Hai ngu6n dao dpng cung pha: V A = - = 2cm; -S^Sz A = 2cm v = Xf = 2.12 = 2Acm/s 2n Cau 46:X = vT = v— = 0.3cm = n{d2 - di) = 2,57r vuong pha 2n Cau 47: A = v r = V — = 2cm 0) M cung pha v6i O khi: 27id2 < P A - O = — - Vai d i = Y A = 11cm 27idi — = k27c -> dz = d i + kX M nam tren AB va gan O nhat d = Khoang each MO: MO = ^dj - dl = 2VlO cm Cau 44:X = vT = v— = 2,5cm 6> v * ^ - - x,r MA-MB 10-5 „ Xet diem M : — - — = —— = Suy ra, tu M va duong trung true AB c6 cue dai (kg ca M)- Y"^' VAT U 12 - TiM TAT lY THUYfT VA BAI TAP TRAC WEHigM - TAP CHIflMG Z: SdNG Cd Cau 51: / = ^ -* A = AOcm Cau 63: Buac song : - = 10cm A = 40cm Phuomg trinh s6ng tai diem N bit ki c&ch O mpt dogn x: {2nx\ sin (cot) u — 2a v = Xf = 4m/s Cau 52: / = 5^ -> A = 20cm -» v = A/ = Im/s Cau 53: A = = 0,8m; - J - = C I M G 2: sANG Cd « A T lY 12 - T(iM TAT LY THMVgT WA BAI TAP TBAC WSHlgM - TAP Xet mgt bo s6ng: byng song M l a d i I m B : ag = 2a sin M i a diem C: ttc = 2a sin Cau 54: / = 4^ A= Im Cau 55: A = = 0,5m; / = 2a = v = A/ = 50m/s = -> byng, nut Khoang thai gian ngSn nhat giiia hai an ma li dao dong cua phan tu tai B bSng bien dao dpng cua phAn tu tai C la A/2 Cau 56:/= 4:^ = 5-2 ( /" ) 2/ + / = 40//Z, 2a(f) i = 50cm 0,2 s => - = 0,2s r = 0,8s Van t6c truyen song: v = - = 0,5m/s Cau 57:/ = ^ = n ^ , Voi / = 200Hz ykv = AOm/s, chon / ' cho n nguyen -> / ' = 60Hz Cau 58: i = 6^ A = 0,6m t; = A/ = 60m/s Cau 59: Be rpng moi bung song: Amax = 2a = 2.1,5 = 3cm So b\ing song: A = = 0,4m; T T T = -* bung song A/2 J = Cau 60: / = (5 + i ) ^ = ^ => / ' = 20//z F Cau 61 62 63 64 65 66 ^ 67 68 69 Dap Cau A •A A D B B C D B 71 72 73 74 75 76 77 78 79 80 Dap kn B D D D B B C D B ^=2 D Cau 76: L i = 1 g = » / i = A CSu 62: / = 12^ /1 \dJ /2 = lO-^M^/m^ Cau 77: Cau 61: — = — f^)' = 70 C Cau 75: ^ = 171 m - L B = 10 Igr = 10 Ig = X = 8cm -^v = Xf = 80cm/s I Cau 78: IA-IB A = 10cm ^ = N 1^ nut s6ng thir = ^OdB => l O l g ^ = 10 => ( = 10/^ CHIfmiG 3: DtM OlfR H A T COfl VAT tt n - Tim TAT LT TW g VA BAl TAP I YT TRACromgM- TAP CHirONG DONG DIEN XOAY CHIEU VAN DE 1: CAC BIEU THlTC CO BAN • Nguyen tic tao dong dien xoay chiSu d\ra tren hi^n tirgng cam ung difn tir Khung day quay mpt tu tnrang d§u, cac duomg cam ung tir vuong goc vai tryc quay va cat mSt phSng chiia khung day • BiSu thurc tu thong: 4> - 4>o cos(ft)t + (p) 00 = NBS: Tu thong cue dai qua cupn day B: Cam ung tir (T) Oi = 2nf (rad/s) cp = (n,B)(,=o) • 8*^^ vecta phap tuyen n va vecta cam ling tir B tai thai diem ban dau • Bieu thuc suat di?n dpng: e = -(f)' = EQ COS (o)t + ^ f) EQ = NBS(o: Suit di?n dgng cue dai • Bieu thuc di?n ap: u = f/ocos ((at + (p^) • Bieu thurc cucrng dp ddng di?n: i = IQ COS (a)t + (pi) En 4^ >/2 all I ifAUV tZ - TOM TAT LY BAl TjP TBAC WEHlgM - TAP CHtfUHB 8: DdHS OI|ll XOAY CHlf e Khi tir thong c6 gia tri bSng mot nira gia tri cue dai thi suat di§n dpng CO dp Ian bSng bao nhieu? Giai: N = 400 vong; S = SOcm^ = SClO'^m^; B = 0,4T; (B = 3000 vong/phiit a Tir thong c\rc dai: 0o = NBS = 0,8Wb t k s6 goc: CO = 3000 vong/phut = 3000x— = IOOTI rad/s 60 b Bieu thirc tir thong: =? 00 cos(ajt + (p) B 71 7t _ 7t vai = (n,B)(.^) ~ ~