Giai Chgn dap an A Cdu 40: D a t d i e n ap u = UoCOsCcot + cp) (Uo va cp k h o n g doi) vao hai dau doan mach mac n o i t i e p gom dien trdf t h u a n , t u dien va cuon cam t h u a n C O t i f cam L t h a y doi dtftfc K h i L = L i hoac L = L2 t h i ci/dng dong d i e n h i e u dung t r o n g doan m a t bang De cifcfng dong dien h i e u dung t r o n g doan mach gia t r i A ^ ( L , + L , ) B CLTC C L, + L dai t h i gia t r i cua L bSng 2L,L, L, + L , D 2(Li + L2) Giai T a c6: I i = I2 Suy r a : ooLi K h i I = led Zi = Z2 (oL, - wC L i + L2 = (oC => L = ^ (oL = TCr (1) va (2) suy r a : L = co'C (1) (2) ^'^^^ Vdy chgn dap an A Cdu 41: M o t v a t dao dong dieu hoa vdri t a n so goc rad/s K h i vat di qua l i dp 5cm t h i no c6 toe la 25 cm/s B i e n giao dong cua vat la A 5,24cm B V c m C 5^3 cm D 10 cm Giai A p dung cong thufc A^ = + (0" = ^ + — - = = > A = 5V2 (cm) Vdy chgn dap an B Cdu 42: H a i iSc dan dao dong dieu h6a t a i cung m o t v i t r i tren T r a i D a t Chieu d a i va chu k i dao dong cua iSc dcfn I a n Itfcft la C^, £2 va T i , T2 B i e t A = He thiirc dung la B = D ^ a c i = i = P T a c : T i = i j ^ ; T = 27i Vg IL - _ L L - »V g Vdy chgn dap an C 186 GiSi Chi ti^t 06 thi TS DH, CB Mon V4t li Cdu 43: Bufc x a c6 t a n so n h o n h a t t r o n g so cac bufc x a h o n g n g o a i , tuf n g o a i , RoTn-ghen, g a m m a l a A g a m m a B hong ngoai C Rcfn-ghen D tuf n g o a i Giai V i bifdfc s o n g bufc x a h o n g n g o a i Idrn hern biidrc s o n g cac bufc x a tuf n g o a i , R o w n g h e n v a g a m m a n e n THN < ^TN < fx < fyVay chgn dap an B Cdu 44: M a c h d a o d o n g d i e n tii l i tirdrng g o m c u o n c a m t h u a n c6 ttf c a m L v a t u d i e n c6 d i e n d u n g C T r o n g m a c h d a n g c6 d a o d o n g d i e n tii t i f d o G o i Uo l a h i e u d i e n t h e CLTC d a i giOfa h a i b a n t u v a lo l a circfng d o n g d i e n cUc d a i t r o n g m a c h H e thufc d u n g l a B Io = Uo A Io = Uo, D Uo = lo Giai N a n g liTofng c u a m a c h d a o d o n g W = CU^ LI 2 ^ In = U , Vay chgn dap an B Cdu 45: C h a t p h o n g x a X c6 c h u k i b a n r a T B a n d a u ( t = ) , m o t m S u c h a t p h o n g x a X c6 so h a t l a N o S a u k h o a n g t h d i g i a n t = T ( k l tCr t = ) , so h a t n h a n X d a b i p h a n r a l a A 0,25No B 0,875No C 0,75No Giai So h a t n h a n X d a b i p h a n r a l a A N = No Vdy chgn Cdu •4 D 0,125No = 0,875No dap an B 46: D a t d i e n a p x o a y c h i e u v a o h a i d a u d o a n m a c h g o m d i e n t r d t h u a n m a c n o i t i e p v d i t u d i e n B i e t d i e n a p h i e u d u n g giiifa h a i d a u d i e n trd v a giuTa h a i b a n t u d i e n I a n l i f t f t l a l O O V v a 0 V S V D o l e c h p h a giuTa d i e n a p h a i d a u d o a n m a c h v a d i e n Ap giOfa h a i b a n t u d i e n c6 16n hkng Gilii Chi ti£t 06 thi TS BH, CO Udn Vdt If 187 Gi^i D o l e c h p h a giufa d i e n a p h a i d a u d o a n m a c h v a d o n g d i e n t r o n g m a c h : tancp = — ^ = -\f3 UR => (p = - — D i e n a p giOa h a i b a n t u d i e n c h a m p h a hcfn goo D o l e c h p h a g i d a d i e n a p h a i d a u d o a n m a c h v a d i e n a p giOra h a i b a n t u d i e n c6 l