mot dien ap xoay chieu on dinh thi cuong dp dong dien hieu dung trong mach Ian lupt la 2A, 1 A, 3A. Khi mac noi tiep ba phan t u R,L,C do roi mSc vao dien ap xoay chieu tren thi cuong dp dong dien hieu dung trong mach la
A. 3 V2 A. B. 6 A. C. 1,20 A. D. 1,25 A.
<Phdn tich vd huamg dan gidi
Theo bai ra, khi mac Ian lupt dien tro thuan R, cupn cam thuan L, tu di^n C vao mot di?n ap xoay chieu U khong doi nen ta c6: vao mot di?n ap xoay chieu U khong doi nen ta c6:
Dien tro thuan: R = — = —
IR 2 • ii,:i^Hn-.>
^ - >u' - V U U : •
Cam khang cupn day: ZL = — = — = U
I I 1
l u - ' ^, V U U
Dung khang cua tu: Zc = — = — Ic 3 Ic 3
Khi mac noi Hep ba phan t u R, L, C do roi mac vao dien ap xoay chieu tren thi: Tong tro cua mach liic nay: Tong tro cua mach liic nay:
3
= 5 u
6
Cuong dp dong dien hieu dung luc nay: I = — = = 1,2A Z Z
6
Chpn dap an C
Vi d u 9: Doan mach AB gom hai doan mach A M va MB mac no'i tiep. Dat dien ap u = 240cos 1007lt + - dien ap u = 240cos 1007lt + -
12 ( V ) vao hai dau doan mach AB thi dien ap tuc thoi hai dau doan mach MB la u MB=120N/2 cos ap tuc thoi hai dau doan mach MB la u MB=120N/2 cos
Di^n ap hieu dung hai dau doan mach A M bang
A. I20V2V. B.C. C. 120V.
l O O n t - -6 ( V ) . 6 ( V ) .
D. 120(V2-l)V
^hdn tich vd hu&ng dan gidi
Bai nay gidi theo so phiee chi mat khoang 10 gidy la c6 dap an, lim y khi gidi chuyen vetoa do cue dqngAZQ con ne'u chua dua vetoa do cifc thi can bam them chuyen vetoa do cue dqngAZQ con ne'u chua dua vetoa do cifc thi can bam them SHIFT 23 = mdy se chuyen vetoa do cue. Cdch gidi nhu sau:
Ta c6: U^B = UAM + "MB ^ "AM = "AB - "MB Ban 2 4 0 Z f ' - 1 2 0 N / 2 Z f Ban 2 4 0 Z f ' - 1 2 0 N / 2 Z f
. 1 2 , = 169,7
Tu day ta thay U^M = = ^ = 120V •s/2 v2 •s/2 v2
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