dau doan mach.
' Humgdan
2,. = z„ = H,|£.„,„,
I 5,D
Khi mac noi tiep, ve gian do vec to trugt, tu tam giac vuong can AMB: Up = Uo = U = 220(V)=>I = 220 Up = Uo = U = 220(V)=>I = 220
40 = 5,5(A)
Tu gian do suy ra dong dien som pha hon dien ap la n/6
=::>ChonC.
I ' J ' \
Bo ttv hien tliiic Vat li LTDII tren henh VTV2. t^p 2 - Chu V^n Blen
5) Dung gian do vec to de viet bieu thiic dong dien hoac dien ap
* Neu cho biet tuang minh cac dai lugng tlii nen dung pliuong pliap dai so hoac phuong phap so phiic de viét bieu thuc. hoac phuong phap so phiic de viét bieu thuc.
* Neu con c6 mot vai dai luong chua biet thi de viét bieu thuc mot each hieu qua nhat la dung gian do vec tọ qua nhat la dung gian do vec tọ
Vi du 1: Mot doan mach gom dien tro thuan R noi tiep voi tu dien c6 dien
dung l/(37t) (mF). Dat vao hai dau doan mach mot dien ap xoay chieu: u = 120cosl007rt (V). Dien ap hieu dung giua hai dau dien tra bang 60 V. u = 120cosl007rt (V). Dien ap hieu dung giua hai dau dien tra bang 60 V. Tinh R va viét bieu thiic dong dien qua mach?
Ạ R = 30 Q va i = 2 V2 cos(l OOTit + 7i/4) (A). B. R = 30 Q va i = N/2 COS(1 OOTit - 7t/4) (A). ^ B. R = 30 Q va i = N/2 COS(1 OOTit - 7t/4) (A). ^ C. R = ^0^/3 Q va i = 4cos(1007it - 7t/6) (A). D. R = 30 p ya i = 4cos(lQ07Tt + K/6) (A). Zc ' Huong dan R = Zc = 30Q _^Z-R + i ( 0- Z c ) ' 3 0( n ) ; U 2 . . u 2 60^2 60^ + vl =^ Uc = 60 = UR 120 i = V2( cos 100TTt + - 4 1 = — (A): 30 - ị30 Chon Ạ • = 272Z1 !*,,V',0?: R
Vi du 2: Dat dien ap xoay chieu u = 60 >/2 cosl007:t (V) vao hai dau doan mach
AB gom hai doan mach AD va DB mac noi tiep. Doan AD gojn dien tro
thuan R mac noi tiep voi cuon cam thuan L = 0,2/7i (H), doan DB chi c6 tu
dien C. Dien ap hieu dung tren doan AD la 60 (V) va tren doan DB la 60 (V). Bieu thuc dong dien qua mach la Bieu thuc dong dien qua mach la
Ạ i= V2cos(1007tt + 7i/4)(A).
B. i = 4.cos(1007rt + 7r/3)(A). ''''' r - t > ' > ' u .