D. di^n ap hieu dung tren tu giam ,\
,I phu thuoc Zc theo
1 1 • It , , ^ - 1 CỎ ( 0 , . . n thuoc 1/(0^ theo kieu ham tam thuc bac 2 nen: — = .
Wo 2
Vi du 1: Cho mach dien xoay chieu noi tiep gom cugin day thuan cam c6 do tM cam L thay doi duoc, tu dien c6 dicM-i dung C va dien tro R, Co hai gia cam L thay doi duoc, tu dien c6 dicM-i dung C va dien tro R, Co hai gia
Cty TISHH M T V If V V H Khang Vl^t
khac nhau cua L la Li va L2 thi dien ap hieu dung tren cuon ram c6 cung mot gia trj. Gia tri cua L de dien ap hieu dung tren cuon cam cue dai la mot gia trj. Gia tri cua L de dien ap hieu dung tren cuon cam cue dai la
Ạ L = (Li + L2)»'. L = a5(Li + L2).
C.L = 2 L i L 2/ ( L i + L 2 ) . D. L = L,L2/(Li + L2).
:,,fioi> ' Humgdan :=ic:/ ;
U Z , u
U L = I-ZL = , , — = I 1 ' UL phy thuoc
N / R M ^ T ^ J(R^.Z^).|T2.ZC.^.T
1/Zi theo kieu ham tam thuc bac 2 nen: — = -^Li—5L2. Ln - ^tlll2_
ZLO 2 " L 1 + L 2 =>ChonẠ V ỉ;;..: v ' . . . .-'^ ) , - • ; ; ' i ^ - - :>•. - ^ ' - r , : ^ ;,!,,.!. „';,-,
Vi du 2: Mach dien xoay chieu RLC khong phan nhanh, dung khang bang 50Q, dien tro thuan R va cuon cam thuan c6 cam khang ZL thay doị Nguai ta dien tro thuan R va cuon cam thuan c6 cam khang ZL thay doị Nguai ta nhan thay khi ZL C6 gia tri ung vai 100 Q va 300 Q thi dien ap hi§u dung tren cuc)n cam c6 cung mc)t gia trj. Tinh R.
Ạ 25 Q. B. 19 Q. C. 50 V2 Q. D. 50 Q, Vo •,hm . ) Huaitgdan ,.!) t-,,. j 7 n ? « ''.u <\h 1 m,-^ • U L = I . Z L = ^ ^ ^ = , ^ , U L phu ^ R ^ . ( Z , - Z c f ( R ^ . Z ^ ) . J ^ - 2 . Z c . - l . l ' 1 1 +
thuoc 1/ZL theo kieu ham tam thuc bac 2 nen: = — — ^ = ^ ^ ^
ZLO 2 R^+z^
, = -(100-^ + 300"' ] => R = 5072 (f^) ^ Chon C. R2+502 2^ ^ V / . R2+502 2^ ^ V / .
Vi du 3: (DH-2009) Dat dien ap xoay chieu u = Uocoscot c6 Uo khong doi va co
thay doi dugc vao hai dau doan mach c6 R, L, C mac nói tiep. Thay doi (o
thi cuong do dong dien hieu dung trong mach khi co = coi bang cuong do dong dien hieu dung trong mach khi co = C02. He thiic dung la : dong dien hieu dung trong mach khi co = C02. He thiic dung la :
Ạ (COI+co2)LC = 2. B. coia)2LC = l .
C. (coi + co2)2LC = 4. D. (coi+(02)2LC = l . .
Huang dan »- ,
Cdch 1: I = — = , ^ , I phu thuoc co theo kieu ham phan thuc
z rr^ ^ y • • y
r
R2 + c o L - coC,
nen: COQ = ^C0jC02 = . / — - CO1CO2LC = 1 => Chon B.
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Afi f r v ;
LC