BAi 1. (5,5 tli6m): Cho mpch dign (hinh 1), v6i U:6,3V, Rr : & : R: :,& :2e, Di€n trd cta v6n k6 rAt lcyn. die, trO cria ampe k6, c6c kh6a K vi ddy n6i kh6ne oarn r.'a. ''" R* a) Tfnh s6 chi cta v6n t6 t<nik,, K, d6;".0 .''i- ,., A b) Khi K1 d6ng, K2 m6; v6n kti chi Uu :4,05V. R1 HEy tfnh: - Cucrng cfQ ddng di6n cy mpch chinh? r,rzI - Gi6 rri cria rliQn tr6 &? e - Higu diQn thiS giira hai di6m CB? c) Jfti Kr, Kz d6u d6ng. Tfnh s6 chi cua v6n k6 vd ampe k6. ; DE THI HAqSINH GIOI CAP THArr{H PHO F{AM HQC 20II * 20t2 Mdn: VgT Li LOp 9 Thdi gian ldm hAi t S0 phrir {I flinh l ke. ar' vao nguon thi cuong d0 dong di6n qua die* PHONG Cmo DUC VA DAO TAO THAI{H pHo'BAC Ciexil'** Bni 3. !13i6y):Hai ampe.k6 co diQn tro lan luq"r rd R1. R2; mQt diQn tro R:3f) va m6t nguon.cliQn-c6 hiQu diQn th6 |h6lg d6i u. N6u m6c r-,aiamfiet6 ,rdi,lil.,ji ,6", ,a,'rX, tiep vdi dion tro R vdo ngu6n_tt iro crri,r6i arnpe r,e rj +-osllNj;k; lr;;r;;';; song song vdi nhau roi mac n6i ti6p vdi di6n tro R uao nguon ;ir*. kc rhu nh6t chi 3,A, ampe tC tnri hai chi 2A. a) Tfnh dien t1o Rr, R2 gua hai ampe b) I{6u chi mic truc iiep dion rro R tru R le bao nhi6u? Bii 1:1S Oi6m;: Cho doan m4ch ctiQn (hinh 2),haib6ng <fdn c6 ghi E1: 2,5V-lW; D2: 6V-3W. eitit ring cdc ddn s6ns M a) Higu diQn th€ gifra hai diu do4n mpch MN? +' b) DiQn tro \ vd rtiQn tro doan mach MN? c) HiQu su6t cria clopn mach MN? Iej 4 1S,S Oi6m): Cho mpch di€n (hinh 3); Bi6t U : 6V, r : 0,5f); 3V-3W, cdc ddy n6i c6 diQn trO f.frOrg OarJtS " - F{inh 2 R =: 1 ,5Q, cldn gh i r I i a) Tfnh cli€n J10 tuone duong cta. m4ch vd cudng d6 ddng rliQn dinh mric cta ddn. Edn sang nhu th6 ndo? b) De ddn s6ng binh thucrng. lguoi ta lay mqt dign tro- R* m6c th0m vAo mach. Hoi R* phai ma; -rru: il6';;. ,\ ,vesud0va tfnh gia tri cla diQn tr& R*trong m6i cach mic? Bei 5. (2 di6m): Dua hai thanh nam ch6m lai gan nhau theo chi6u mfri t6n nhu hinh cria hai thanh nam ch6m titip xric ,huu thi c6c dinh s6t roi xuon!. uie,, tO OiCu gi? Ndu c6 mQt thanh nam ch6m vd m6t thanh I{inh 3 v0" Khi hai eu'c tuong dd chunpr thdp gi6ng hQt nhau, hdy dga vdo ket lupn trdn dd ;lri ra cdch tim duoc thanh nio lA thanh nam chAm ma kh6ng s* dUng th6m vAt dUng gi kh 6c? Ho vd ftn . .''i- ,., A b) Khi K1 d6ng, K2 m6; v6n kti chi Uu :4,05V. R1 HEy tfnh: - Cucrng cfQ ddng di6n cy mpch chinh? r,rzI - Gi6 rri cria rliQn tr6 &? e - Higu diQn thiS. m6t nguon.cliQn-c6 hiQu diQn th6 |h6lg d6i u. N6u m6c r-,aiamfiet6 ,rdi,lil.,ji ,6", ,a,'rX, tiep vdi dion tro R vdo ngu6n_tt iro crri,r6i arnpe r,e rj +-osllNj;k;. vd ampe k6. ; DE THI HAqSINH GIOI CAP THArr{H PHO F{AM HQC 20II * 20t2 Mdn: VgT Li LOp 9 Thdi gian ldm hAi t S0 phrir {I flinh l ke. ar' vao nguon thi cuong d0 dong