Cdu 18: M o t m a y tSng ap c6 cuon thuT cap mac vdri dien t r d thuan, cuon SOT cap mSc vdri nguon dien xoay chieu T a n so dong dien cuon thuf cap: A CO the nho horn hoac lorn horn t a n so dong dien cuon scf cap B b a n g t a n so dong dien t r o n g cuon stf cap C luon nho hcfn t a n so dong dien t r o n g cuon sof cap D luon \dn hcfn t a n so dong dien t r o n g cuon scf cap GiSi T a n so dong di§n t r o n g cuon thuf cap bang t a n so dong dien cuon scf cap Vg,y chgn dap an B Cdu 19: M o t doan mach dien xoay chieu gom mot t u dien va mot cuon cam t h u a n mSc n o i t i e p Do lech pha giufa dien ap d h a i dau t u di$n di§n ap of h a i dau doan mach bSng A - B - - C hoac 7t D - hoac - - - Ta c6: Neu Z L > Zc t h i uc lech pha n vdri u: Neu Z L < Zc t h i uc cung pha vdfi u Vdy chgn dap Cdu 20: an C M a c h chon song cua mot may t h u song v6 tuyen gom cupn cam t h u a n c6 dp tii cam — v a Jt t u dien c6 dien dung C thay doi • • * dUcfc Dieu c h i n h C = — pF t h i mach t h u di/ofc song di$n tCf c6 btfdc s6ng bang: A 300 m B 400 m C 200 m D 100 m Giai Taco: = 2;ICVLC = t \ P ^ - " = 0 m Vdy chon dap an B Cdu 21: Dat dien ap u = 150 V2 cos 100Tit (V) vao h a i dau doan mach gom dien t r d t h u a n , cuon cam t h u a n va t u dien m^c n o i tiep t h i dien 38 GiSi Chi ti6t (36 thi TS OH, CB M6n V$t II ap hieu dung giOTa h a i dau dien t r d t h u a n l a 150 V He so cong suat cua doan mach l a : c i B A D Giai rr ^ 150 , Ta co: cos(p = —U- = 150 = Vdy chgn dap an B Cdu 22: M o t v a t dao dong dieu hoa c6 chu k i 2s, b i e n 10cm K h i v a t each v i t r i can bSng cm, toe cua no b k n g L A 18,84 cm/s B 20,08 cm/s C 25,13 cm/s D 12,56 cm/s Giai Ta c6: co = — = 7i T v = a ) V A ^ - x ^ = ; i / l ' - ^ =871 = 25,13 cm/s Vdy chgn dap an C Cdu 23: H i n h chieu cua m o t chat diem chuyen dong t r o n deu l e n m o t difdng k i n h cua quy dao co chuyen dong la dao dong dieu hoa P h a t bieu nao sau day s a i ? A T a n so goc cua dao dong dieu hoa bang toe goc cua chuyen dong t r o n deu B B i e n dp cua dao dong dieu hoa b k n g ban k i n h cua chuyen dong tron deu C Lire keo ve t r o n g dao dong dieu hoa c6 I d n b k n g dp I d n liTc htfdng t a m t r o n g chuyen dong t r o n deu D Toe CLfe d a i cua dao dong dieu hoa b k n g toe d a i cua chuyen dong t r o n deu Gik'i P h a t bieu sai l a : Life keo ve t r o n g dao dong dieu hoa co dp lorn bkng dp I d n lire hLfdng t a m t r o n g chuyen dong t r o n deu Vdy chgn dap an C Cdu 24: T r o n g mach dao dong l i tudng gom t u d i e n co d i e n dung C vk cupn cam t h u a n co dp t\X cam L , dang co dao dong d i e n tCf txi B i e t Giai Chi liet a4 thi TS DH, CD M6n Vat If 39 hieu dien the ban tu la ^ CLTC dai giiJa hai ban tu Ik UQ K h i hieu dien the giuTa hai t h i cUdng dong dien mach c6 Idn bang: A.'AK B \ ! ^ V C V L Taco: - C U ^ ° C \ j ^ V C =icu^+-Li^ « i c u ^ 3„^^, ° " V L = i IcU^+-Li^ •4 ° Uo f C V L Viay c/ion ffdp an D Cau 25: Theo thuyet Itfofng tuf anh sang, de phat anh sang huynh quang, moi nguyen tijf hay phan tuT cua chat phat quang hap thu hoan toan mot photon cua anh sang kich thich c6 nSng liTOng de chuyen sang trang thai kich thich, sau A giai phong mot electron ttf c6 nang lUtfng nho han e c6 mat mat nang Itfc/ng B phat mot photon khac c6 nang lifong Idn htfn £ c6 bo sung nang lufgrng C giai phong mot electron t\i c6 nang Itfcfng Idn han e c6 bo sung n^ng liicfng D phat mot photon khac c6 nang li/dng nho htfn s c6 mat mat nang liTtfng Theo thuyet liitfng tuf anh sang, de phat dnh sdng huynh quang, m6i nguyen tuf hay phan tuf cua chat phat quang hap thu ho^n toan mot photon cua anh sang kich thich c6 nang Itfcfng s de chuyen sang trang thai kich thich, sau phat mot photon khac c6 nSng li/gfng nho hcfn e c6 mat mat nang liTcfng Vdy chqn flap an D Cdu 26: Trong t h i nghiem Y-ang ve giao thoa anh sang, chieu vao hai khe dong thcfi hai anh sdng dcfn sac c6 bi/dc song A,i = 0,66 [xm va X,2 = 0,55 |4.m Tren man quan sat, van sang bac cua anh sang c6 bu"dfc song X1 trung vdi van sang bac may cua anh sang c6 birdc song X, 2? A Bac B Bac 140 C Bac _ D Bac GiaichitigtdethiTSOH, CDMfln V$tl! ... dap an B Cdu 22 : M o t v a t dao dong dieu hoa c6 chu k i 2s, b i e n 10cm K h i v a t each v i t r i can bSng cm, toe cua no b k n g L A 18,84 cm/s B 20 ,08 cm/s C 25 ,13 cm/s D 12, 56 cm/s Giai... cm/s Giai Ta c6: co = — = 7i T v = a ) V A ^ - x ^ = ; i / l ' - ^ =871 = 25 ,13 cm/s Vdy chgn dap an C Cdu 23 : H i n h chieu cua m o t chat diem chuyen dong t r o n deu l e n m o t difdng k i... dap an C Cdu 24 : T r o n g mach dao dong l i tudng gom t u d i e n co d i e n dung C vk cupn cam t h u a n co dp tX cam L , dang co dao dong d i e n tCf txi B i e t Giai Chi liet a4 thi TS DH,