D. dong dien tire thoi trong mach bang tong cac dong dien tire thoi qua cac p h a n t i r sai vi d o n g d i e n t u c t h o i t r o n g m a c h k h o n g being t o n g cac d o n g
Vay dapanC
C a u 5 : Dat di?n ap u = Uocoscot vao hai dau doan mach RLC noi tiep co L thuan cam thi dogn mach xay ra cpng huong. Gpi i la cuong dp dong di^n tuc thoi trong doan mach, P la cong suat tieu thu cua mach; utva UR Ian lupt la di^n ap tuc thoi giija hai dau cupn cam va giira hai dau d i ^ n tro. Quan h?
nao sau day khong diing? t, „ , ; ,
A. u cung pha v o i 1. .2
C.P = R R
B. u tre pha so v o i UL goc —. ^ « D. U = UR.
^hdn tich m hu&ng dan gidi ' ' '
Khi doan mach xay ra cpng huong thi u cung pha VCJI i ( A dung), u tre pha so v o i UL goc ^ (B dung), u cimg pha v o i UR nen u = UR (D diing), P la,cong
u^
suat tieu thu ciia mach P = — ;t —_ nen (C sai).
Cau 6: Dat dien ap xoay chieu on dinh vao hai dau doan mach AB gom hai doan mach A M va MB m5c noi tie'p. Bie't dien ap hai dau doan mach A M va
dien ap hai dau doan mach M B lech pha nhau goc 7T/3 rad. Tai thoi diem ti gia tri tuc thoi cua hai dien ap U A M va UMH deu bang lOOV. Liic do, di^n ap
tuc thoi hai dau mach A B c6 gia trj bang
A. 100N/2V B. 200 V C. lOOV D I O O V S V
<Phdn tich vd hu&rig ddn gidi
Ta luon co gia trj dien ap tuc thoi UAB = UAM + UMH
Tai t = ti thi U A M = UMH = lOOV => UAB = U A M + UMB = 200 (V). C h p n dap an B
Cau 7: Dat dien ap xoay chieu co u = 100 N/2 cos(a)t) V vao hai dau mach gom dien tro R noi tie'p voi tu C co Zc = R. Tai thai diem di§n ap tiic thoi tren dien tu la 50V va dang giam thi di^n ap tuc thai tren tra la