- Huongdan • Z'^^^i^J
0,125 B 0,87 C 0,5 D.0,75 '
Huang dan 'ÍlOr i . : '1 ,tj - ,JS +
U 2 = U ^ + ( U L - - U C ) ' _ j l 2 0 2 = u | + ( U L - 1 2 0 f | U L = 6 0 . 1 : ? ^c=^la=^l+^i l l 2 0 2 = U | + u 2 U K = 6 O V 3 U coscp = = 0 , 8 7 ^ Chon B. ; M i , , , «'lU f!;,Ue , < , . - i : „ , , . „ , ,r,,j.-. U ' ' . . v i L i ' ^--.^^•5!•M,.=•'I •viuVVv'^(;'')!\
V i d u 16: M o t doan mach dien xoay chieu RLC khong phan nhanh, cuon day c6 dien tro thuan. Dien ap hieu dung giiia hai dau doan mach, tren dien tro R, tren cuon day va tren tu Ian lugt la 75 (V), 25 (V), 25 (V) va 75 (V). He so
cong suat ciia toan mach la ' Ạ 1/7. B. 0,6. C. 7/25. W'tKH D. 1/25. i-
B o t r p k i c n t h i i c V^t l i LTDH t r e n kenh VTV2. t a p 2 - Chu Vdn B i c n
Huong dan
U- = (U K + + (U, - U^.f = + Uf ) + Uf, + 2U„U, - 2U, Ue + U^^
73-=25^+ 25-+ 2.25.U,-2U, .75 + 75- ^ \ , , i
f U , =20(V) Up + U • ' • " *•
[ U , - 15{V) U • ( ^iJ ,1 » ,
V i d u 17: Doan mach dien xoay chieu mac nói tiep gom tu ctien, dien tra thuan va cuon cam thuan. Dien ap hieu dung 6 hai dau doan mach va tren cuon cam Ian ktot la 360 V va 212 V. He so cong suát cua toan mach coscp = 0,6. Dien ap hieu d u n g tren tu la
Ạ 500(V). ^ B. 200 (V). C. 320 (V). D. 400 (V). ,,5,^
! , , . , , . , , A , , r.: .r^:' m -Ó . ^ " ' ^ - " S , , , „
cos(p = ^ = 0,6=^U|, =0,6U = 2 I 6 ( V ) >,n,'r*^nit\ (bi ill
U- = Uf, +(U| - U^.)^ => 360- = 216- +(212- U(.)- ^ =500(V) Chon Ạ
V i d u 18: Doan mach dien xoay chieu mac no! tiep gom tu dien, dien tro thuan
va cuon cam thuan co cam khang 80 Q. Dien ap hieu d u n g a hai dau doan
mach va tren tu Ian luot la 300 V va 140 V. Dong dien trong mach tre pha so voi dien ap hai dau doan mach va he so cong suát cua mach coscp = 0,8. C u o n g do hieu d u n g dong qua mach la
Ạ 1 (A). B. 2 (A). C. 3,2 (A). D. 4 (A).
Humtgdan
Z, >Z^-=>U| >Uc;coscp = - ^ = 0,8 =ịU|, =0,8U = 240(V) " ' ' t ' . U- = Uf^ +(U| - Ue)" ^ 300- =240- + { U , -140)- =>U| =320(V)
^ = 4 ( A ) ^ Chon Ạ ^'5'"
Zi
Chil y: NCni hict cCm;^ siid't tiC'u thu trcii toan mach de tinh dien tnr Iioac cos(p ta dim vao con;^ thúc: P = l~R = • . . .
R ^ + ( Z , - Z J -
V i d u 19: Dat vao hai dau ctoan mach A B mot dien ap xoay chieu:
u = 400cos(1007rt) ( V ) . Mach AB gom cuon day co dien tro thuan R co do t u cam 0,2/7: (H) mac noi tiep voi tu dien co dien d u n g 100/K (HF). Neu cong suát tieu t h u R la 400 W t h i R bang : ..
CtyTNHHMlTVDVVtlKhang V i f t Ạ 5 ạ C. 15 Q hoac lOO Q. Z, =coL = 2 0 ( n) ; Z e = — = 100(Q) P = 1'^R = - R = wC B. 10 n hoac 200 Q. D. 40 0 hoac 160 Ọ Huong dan i , v . : i o ! : •;,d ii hh V/ Oị«,) >; «!•(•' r'^•.f R ^ + ( Z , - Z c ) ^ 400 = 200r2R R^ +(20-100)^ , - 200R + 6400 = 0 : R = 40(D) Chon D. ^ >iH R = 160(Q)
V i d u 20: Dat vao hai dau doan mach mot dien ap xoay chieu co gia t r i hieu dung 200 V . Doan mach g o m cuon day co dien tro thuan R co cam khang