C. Thay do iL de Uimax D Thay do if de Ucma
A. 150Q B.20Q C.60Q D.50Q.
^hdn tich vd huong ddn gidi
(0 thay doi, cuong dp dong dien khong doi nen ta c6 h$ thuc (***)
C0jC02 =
LC
K h i tan so coo mach cong h u o n g nen: L U R Theo bai ra:
C^ 2R2 =R2 + ( Z L I - Z L2 ) ' = > R = Z L I - Z L2
UN/2 u
L = 1007t-807i.- = 60n 71
C h p n dap an C
:au 2: Cho mach RLC noi tiep, Dat vao hai dau doan mach m p t hi?u di?n
the xoay chieu on d i n h c6 tan so f = 50Hz. D i ^ n d u n g cua t u d i # n C = i ^ F •
1 3
K h i L = L j = — H va L = L2 = — H thi h i f u di^n the 6 hai dau cupn day c6
7t 7t
gia t r i hi?u d u n g n h u nhau. D p t y cam L de U L max la A . A H 271 B i n n C i - H 371 D . - I H ~ 471
i'hdn tich vd huang d&n gidi
Khi CO hai gia t n L = Li hoac L = L2 cho ciing gia trj U L thi gia t n cua L lam cho U: m.ix khi:
Z L + Z 1 -^L2
« „ L = i ^ i^ ^ ^ l ^ => L = = = f (H)
Chpn dap an A
C a u 3 : M o t mach dien xoay chieu mac nol tie'p gom cuon cam thuan L, tu
dien C va dien tro R. Dat vao hai dau doan mach mot dien ap xoay chieu:
u = U,)Cos(wt)V, Ul) khong doi, to thay doi dugc. Dieu chinh ut thi thay khi
a) = uw trong mach xay ra cong huang, cuong do dong dien hieu dung la
Im.x, con khi co = wi hoac co = un thi dong dien trong mach c6 ciing gia tri hieu dung I = ^ ^ . Cho L = 1/n H , co, - 0 ) 2 = 15071 rad, tim gia trj R cua
mach dien?
A . R = 50 Q B. R = 7 5 . Q C. R = 3 7 , 5 . Q .
^hdn tich vd hu&ng dan gidi
(0 thay doi ma I khong doi nen ta c6:
D. R = 150.Q. Theo de cho: I, = l 2 _ 1 _ L C 1 (o,C U 1 U R2 + co,L N/3 R « 5 R ^ = R ^ + co.L - (o,C = R^ + ( c o, L- M 2 L f . R = (Oj - (O2 1 .1507: = ^ = 7 5 Q Chgn dap an B
C a u 4 : Mach dien xoay chieu RLC ghep noi tie'p trong do cuQn day thuan
cam CO do t u cam 1/n (H) tu d i ^ n c6 d i ^ n dung C thay doi dugc. MSc mach
vao mang dien xoay chieu tan so 50Hz. K h i thay doi C thi u n g v a i hai gia tri
1 0 -4 1 0 -4
ciia C = C , = - ^ ( F ) va C = C2 = " ^ ( F ) thi dien ap h i ^ u dung giua hai dau tu di?n b3ng nhau. Gia tri ciia R la:
A . R = 2 0 N / 5 Q B . R = 1 5 0 Q C.R=2oV35Q D.R=loV20Q
^hdn tich vd huang ddn gidi
Gia tri C biSn thien Ucnax lien he vai hai gia trj C| va C2 Uc c6 cung gia trj la:
J__\ (
<=>c)C = ^
-1-4
10"^ 10-^
^ C = ^ = - 2 z ^ ^ = ^ ( F ) ^ Z , = 2 4 0 Q Ta lai c6 C bien thien de Ucmax lien h | qua R va Zi,:
• i
R2 +Z2
^ R = yjz^Z^-Zl = V240.IOO-IOO2 = 20V35Q
Z c =
Chpn dap an C
C a u 5 : Cho mach xoay chieu R, L, C mac noi tie'p, v o l C thay doi. D i ^ n ap
xoay chieu dat vao 2 dau mach u^g = 100%/2cosl007:t(V), R = 10073Q, L
khong doi. K h i C tang 2 Ian thi cong sua't tieu thu khong doi, nhung cuong
do dong d i ^ n c6 pha thay doi 1 goc ^ . Tinh cong sua't tieu thu cua mach? A . 25V3W
Ta c6: =
B . 5 0 N / 3 W C . lOoVsW
'Phdn tich v>d huang ddn gidi
D . I O O W
1
~2 ^4^-
Vi i thay doi 1 goc 60" nen Jf!li2—^^""i^i ^ fg^^g ^ 1 + tan(j)j.tan<t)2
Thay Z L theo Z^ bien doi ta dugc
-Zc^ - Z ^ R + 2N/3R2 = 0 Z C = 400 -> Z L = 300
Suy ra P =
C a u 6 : Mach xoay chieu n o i tiep g o m cupn day thuan cam L , di#n t r o R = 150N/3Q va t u d i f n C. Dat vao hai dau doan mach hi?u di?n the
u = UoCos(Bt(V) v o i CO thay d o i dug-c. K h i coj = SOnrad / s hoac
©2 = 2007trad / s t h i cuong d o dong di^n trong mach c6 gia t r i hi?u dung n h u nhau n h u n g l^ch pha nhau — . Cam khang cua cuon day k h i co = coj la:
A. = lOOQ B. = 150Q C. Z^^ = 180Q D . Z^^ = 250Q 'Phdn tick v>d huamg ddn gidi 'Phdn tick v>d huamg ddn gidi
CO thay doi m a I khong doi nen ta c6: Z j Z j < ^ Z L I - Z ( ; i = - (Z L2 - 2 ^ 2 )
C0j(»2 = J _
LC = COn • cooL = • tan (pi = - tan => cp^ = -CP2
< P l = V u - ^ i i 2rt ^ 7 1 c O j L - tancpj =• cOjC CO1L ^^—zr- ^ 1-1 cojC ^ _ Rtancpj _ R R 150 Vs. tan R COn = - ( c o i - c o 2 ) COj -CO2 27t.25-271.100 - 0 , 9 5 5 = > Z L =150n L > 0 = > 9 i = - - C h p n dap an B Chnyta 8 B A I X O A I M M A Y € > l l ^ N D A N G 1 : M A Y P H A T D I E N X O A Y C H I E U 1 P H A *
p - so cap cue tir
P H l / Q N G P H A P