Hieu dien the tiic thai a hai dau doan mach cung pha vdi hieu dien thg tiic thai a hai dhu dien tra R.. Hieu dien the hi?u dyng tren cupn cang giam.. Mac doan mach tren vao dien dp xoay
Trang 1CHlfflHBSlDdHSnigHllBAYCmgO VAl H 1 2 - T J M T A T L Y THUYgt V A B A I T ^ P T R A C HmitU - T A P 1
Cau 68: (De thi dai hpc nam 2007) D5t hieu di?n the u = Uosincot (Uo
khong doi) vao hai dhu doan mach RLC khong phan nhanh BiSt dien tro
thuin cua mach khong d6i Khi c6 hien tucmg cong huong dien trong doan
mach, phat bieu nao sau day sal?
A Hieu dien the hi?u d\ing a hai dau difn tra R nho hon hieu dien
thk hi?u dung a hai diu doan mach
B Cuomg do hi?u dvmg cua dong dien trong mach dat gia tri Ion nhat
C Hieu dien the tiic thai a hai dau doan mach cung pha vdi hieu
dien thg tiic thai a hai dhu dien tra R
D Cam khang va dung khang cua doan mach bing nhau
Cau 69: Mach dien khong phan nhanh g6m dien tra thuin R = lOOQ, cuon
day thuan cam c6 dp t\ cam L = - H v a tu di§n c6 di?n dung C thay doi
dugc Mac mach dien vao ngu6n (220V-50Hz) D6 cucmg do hi?u d\mg qua
mach CO gia tri cue dai thi gia tri cua C la
B.1«1F C.H21F D.^^J
" n n n
Cau 70: Trong doan mach RLC n6i tiep dang xay ra cpng huong di$n Tang
dkn tan s6 dong dien va giO nguyen cac thong s6 cua mach, ket luan nao sau
day la dung
A He so cong suat cua doan mach giam
B Cucmg do hi?u dung cua dong di?n tang
C Hieu dien th6 hi^u dung tren tu dien tang
D Hieu dien the hi?u dyng tren cupn cang giam
Cau 71: Trong mach dien xoay chiau g6m di?n tra thuAn R, cuon day thudn
cam L va t\ dien C mic n6i tilp Liic dau, mach c6 tinh cam khdng, nh
giam thn s6 cua dong di?n mgt lugmg nho (sao cho tin so van nho han gia tri
^ ) t h i
27tVLC
A dung khang giam B cam khang tang
C t6ng tra cua mach tang. D t6ng tra cua mach giam
Cau 72: Cho mpt doan mach di?n xoay chik AB g6m R, L, C mac noi tiep
CO R = 200Q D§t vao hai dhu doan mach nay mot hieu dien thS xoay chigu
CO gia tri hi?u d\mg 220V va tan s6 thay d6i dugc Khi thay doi thn s6, cong suat tieu thv c6 thS d^t gia trj cue dai bang
17?
V A T LY 1 2 - IIJM T A I li IHUYgT W A B A I T A P T R A C WSHlgM - T A P 1 CHItlfHB 3: OdHB fllgH XOAY CHlgO
Cau 73: Mpt doan mach khong phan rJianh g6m dien tra R, cugn day thuSn
cam L v^ tu di?n C mac noi tiSp Mac doan mach tren vao dien dp xoay
chik hinh sin thi di?n dp tiic thai a hai dau d o ^ mach cung pha vai cucmg
d^ dong dien trong mach Kk luan ndo sau day khong dung?
A He so cong suat cua mach dat gia tri cyrc dai
B Cam khang bang dung khang
C Dien dp hi?u dyng a hai dau cugn day L va hai dau dien tra R
bang nhau
fD Di?n dp hieu dyng a hai dau^dogn mach va hai diu dien tra R
bang nhau
Cau 74: Dung khdng cua mgt m?ich RLC mic noi tiep dang c6 gia tri nho han
cam khang Muon xay ra hi?n tugng cgng huong dien trong mach ta phai
A Tang di?n dung cua tu di?n
B Tang h? s6 tvr cam cua cugn day
C Giam di?n tra cua mach
D Giam tan so d6ng di?n xoay chieu
Cau 75: Chgn cau dung Mgt doan mach RLC mic noi tilp, cugn day thuan
cam Biet ring dien dp hi?u dyng a hai dau cugn cam L va hai dau tu dien C bang nhau Dien dp tiic thai gifta hai dau doan mach va dong dien trong mach
A cvmgpha B sampha C trepha D vuongpha
au 76: (Be thi dai hpc nam 2007) D$t hi?u di?n thS u = 100>^ sinlOO;rt (V) vao hai dau doan mach RLC khong phan nhanh vai C, R c6 do Ion
khong d6i va L = — H, khi do hi?u di^n th6 hi?u d\mg or hai dhu moi phin tii
g R, Lva C CO dg Ian nhu nhau Cong suat tieu thy cua doan mach la
Cau 77: Mgt doan mach gom di?n tra R, cu^n clay thuan cam c6 dg t\ cam
L va tu di$n c6 di?n dung C = 15,9 // F mdc noi tiep Mac mach dien vao
nguon (220V-50HZ) thi di?n dp hi?u d\mg 6 R Id 220V Gid tri cua L Id
A.0,318H B.0,636H C 0,159H D 0,468H
1 7 3
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Cau 78: Doan mach noi tiSp c6 difn tra thuan R, cupn day thuan cam c6 do
0,4 10"^
tu cam L = - ^ H va t\ di?n c6 di?n dung C = F D8 di?n ap hai dhu
doan mach cung pha voi di$n ap giiia hai dhn dien tra R thi tan s6 dong dien
C O gia tri
A lOOHz B 75Hz C 50Hz D.25Hz
Cau 79: (De thi cao dSng nSm 2008) Dat mpt hi?u di?n thg xoay chik c6
tan so thay doi ducrc vao hai dau doan mach RLC khong phan nhanh Khi
tan so dong dien trong mach ion hern gia tri "^^J^^^y^^
A Hi$u dien the hi?u d\ing giura hai dau di?n tra bang hi?u di?n the
hieu dung giiia hai dau do^n mach
B Hieu dien thi hi?u dyng giura hai dau cupn day nhd hom hieu
di?n the hi?u d\mg giiia hai ban t\ di?n
C Dong di?n ch^y trong doan mach cham pha so voi hi§u di?n the
giura hai dau doan mach
D Hi?u di?n the hi?u d\mg ^iiia hai dau di?n trd Ian hom hi?u difn
the hieu dimg giiia hai dau doan mach?
Cau 80: Doan mach RLC n6i tiSp voi ampe dugc mac vao di?n ap xoay
chieu u = 200cos(1007rt) (V) Cho biet trong mach c6 hi?n tugmg cpng
huong di?n va so chi cua ampe kS la 2A Gia tq cua R la
A lOOfl B.50Q C.50V2Q D lOOVZQ
Cau 81: Mach di?n g6m RLC noi tiSp vao mang di?n xoay chiSu c6 di?n ap
u =Uocosa)t(V) Cho hik khi = lOnrad/s va 0)2 = 160nrad/s thi
cucmg dg hi?u d\mg trong mach nhu nhau Tinh gia trj cua (o dl cucmg d?
dong di?n qua mach c\rc d^i
A 17071 rad/s B 85 TT rad/s C 1 S O T T rad/s D.407r rad/s
Cau 82: Cho mpt doan m^ch g6m di?n tra thuSn R, cupn day thuan cam c6
1 25 ,
do tu cam L =—H va t\ di?n c6 di?n dung C =—}iF n6i tilp Hi?u di?n 7t 7:
thS xoay chieu dat vao hai dku mach 6n djnh va c6 bieu thuc u = Uosin(1007rt)
D6 hi?u difn the hai dau doan mach l$ch pha 7i/2 so voi hi?u di?n thS giua hai
dau bO t\ thi phai ghep the nao va gia trj cua C bang bao nhieu? A ghep C'song song C, C = 75/71 ^iF
IT/I
If AT lY W - m TAT lY THUYgT » A BAI TAP TBAC MfiHlgM - TAP 1 CHinniB3:DdMEBlilX0AYCHl£u
B ghep C'n6i tigp C, C = 75/n ^iF
C gh6p C'song song C, C = 25 ^F
D ghep C'noi tigp C, C = 1 GO ^iF
Cau 83: (De thi cao dSng nam 2008) Mot doan mach RLC khong phan
nhanh g6m di?n tra thuan lOOQ , cuon day thuan cam c6 he s6 tu cam
Cau 84: Cho hai doan m^ch khong phan nhanh: i?,i^C, va/Jj^jC^co tan s6
rieng dh\i bang/o Khi mac noi tilp hai doan mach nay thi tin s6 rieng cua
mach do la
A 2/0 B.3/0 C /o D 0,5/0
• BIEN THIEN R, L, C
Cau 85: (De thi dai hQC nam 2008) Doan mach di?n xoay chieu gom bien
tra R, cuon day thuSn cdm c6 do t\ cam L ya t\ di?n c6 di?n dung C mac
n6i tilp Bilt hieu di?n thg hi?u dun^ hai diu doan mach la U, cam khang
ZL, dung khang Zc (voi Zc ZL) va tan so dong di?n trong mach khong d6i Thay doi R dSn gia trj Ro thi cong suit tieu th\ cua doan mach dat gia tri cue dai Pm, khi do:
A.Ro=Z,+Zc - ~ U
7
C P = — " Ro D Ro = ZL-Ze Cau 86: Mot dogn m?ch khong phan nhanh gom tu di?n c6 dien dimg
C = ——F va bien trd R Mac vao hai dau doan mach mpt di?n ap xoay
chiSu (220V-50Hz) Dieu chinh hikn tra de cong suat tieu th\ Ian nhat thi
gia tri hien tra la
A.100Q B.50Q C.120Q D.150Ci
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Cau 87: (De thi cao dSng nSm 2010) Dat difn dp u = f/VZcos (cot) (V)
vao hai dSu doan mach gom cupn cam thuSn mic n6i tiep voi mpt bien tra
R iTng voi hai gia tri Ri =20 Q va R2 = 80 Q cua biSn tra thi cong suat tieu
thu trong doan mach d8u bang 400 W Gia tri cua U la
A 400 V B 200 V C 100 V D 1 OON/2 V
Cau 88: Cho mach xoay chieu khong phan nhanh g6m dien tra thuan R
(thay doi dugc) va cupn day thuan cam c6 dp t\ cam L Hieu di?n th6 hai
dau mach u = Uyfl cos(l OOTrt) (V) Bik rang khi R = 180ri va R = 3200
thi m^ch tieu th\ cung cong suat P = 45W Gia tq cua L va U la
A.L= - HvaU= lOOV B L = — H v^U = lOOV
thu&i cam L = Hva bien trd R Dat vao hai dau doan mach hi?u di?n
thS u = 200COS (lOOTTt) m.Thay doi R de cong suat mach c\rc d^i Gid trj
cua R va cong suat luc nay Ian lugrt la
250
A. 120a va — W. B.nOQ va 250W
250 C.280t}vd250W D 2 8 0 n v a — W
3 Cau 90: Mpt m^ch di^n xoay chieu khong phan nhanh gom cupn day (c6
di|n tr6 thuan Ro = lOn dp ty cdm L = y ^ H ) , ty di?n c6 di?n dung
10-^
C = — v a di?n tro thuan R thay doi dupe D|t vao hai dau do?in m^ch
hi?u di^n the xoay chieu u = 100>/2cos(100;rt) (V) Cong suat tieu th\ tren
doan mach d^t gid tri cvrc dai khi R c6 gid tri:
A. l i o n B 78,1« C 50Q D 148,7Q
178
DitT lY 1 Z - T O M TAT LY THUYgl VA BAl TAP T B A C WGHIEM - T A P 1 CHlfltHB 3: BflHS DlEll XjmHjgB
Cau 91: Mot mach dien xoay chiSu khong phan nhanh gom cupn day (c6
dien tra thudn Ro = 30fi, dp tu cam ^ = y ^ H ) , ty di?n c6 di?n dung
C = F va dien tra thuan R thay d6i dupe Dat vao hai dau doan mach
71
CO hieu dien the xoay chieu u = 100V2cos(1007xt) (V) Cong sudt tieu thu
tren R dat gid tri cue d^i khi R c6 gid tri:
A IIOQ B 78,1Q C 50Q D.'l48,7fi Cau 92: Mot doan mach xoay chiSu khong phan nhanh g6m cupn day (dien
fj:au 93: (De thi dai h<}c nam n5m 2007) DSt hi?u di?n the u = Uosincot (Uo
va CO khong d6i) vao hai dau doan m?ich RLC khong phan nhdnh Biet dp t\ cam va di?n dung dupe giii khong d6i Dieu chinh trj s6 di?n tra R de cong
sudt tieu thu cua doan mach dat c\rc dai Khi do h? so cong sudt cua doan
mach bang
V2
A 0,5 B.0,85 C ^ D 1
Cau 94: Mach dien xoay chiSu g6m biSn tra R ya t\ di?n C n6i tiep Mac
machi vao mang di?n xoay chik (220V-50Hz) DiSu chinh R ta thay khi R c6
hai gid tri 25 Q va 100 Q thi cong suat nhu nhau Gid tri di?n dung C
Trang 4CHlfmiG3:Bi>H8DlC»HAYCHig| ><T t» « - TtM T A T TWYfT Mk lAl T A P T B A C WaneB - Iht 1
Cau 96: Mach di|n xoay chieu khong phan nhanh gom cupn day thu^ cam
0 2
CO do ty camL = - ^ H va bien tra R Dat vko hai dau dogn m?ich mpt di^n n
ap xoay chieu c6 t ^ s6 50Hz Khi R = lOfl, cong suk cua mach lOW Gia
tri khac ciia bi^n tra ma cong suat van la lOW la
A 15fi B lOQ C.20n D.40Q
Cau 97: Cho mpt dogn m?ich di?n xoay chieu g6m mpt bien tra R mSc n6i
tilp voi mOt cupn thuSn c ^ c6 dp tvr cam L =—H Hieu di?n the hai dku
doan mach on djnh \k c6 hiku thurc u = 100cos(1007rt) (V) Thay doi R, ta
thu dupe c6ng suat tod nhi?t c\rc daii tren bien tra bSng
A 12,5W B.25W C SOW D lOOW
Cau 98: MOt doan mach g6m bien tra R mSc n6i tiep voi cupn day c6 dp tu
cam L = 0,08H vk di?n trd thuan r = 32Q D^t vao hai dliu doan mach mot
hieu di$n thk dao dpng dieu hoa on djnh c6 tan s6 goc 300 rad/s De cong
suat toa nhi?t tren bien trd dat gid tr; 16n nhat thi di^n tra cua bien tr6 phai
CO gia tri bSng bao nhieu?
Cau 99: Mpt do?in mach khong phan nhanh gom bien tra R, cupn day thuSn
cim L = — H vd t\ di?n fc6 di?n dung C = DSt vao hai dau doan
mzich mpt hi?u di?n thI on dinh c6 hiku thiic u = U V2 cos(1007it) Khi thay
doi R, ta thdy c6 hai gid tri khdc nhau cua bien tra Id Ri va R2 ung voi cung mpt
cong sudt tieu thy P cua mach Ket luan nao sau day Id khong dung
TT 2
A R1.R2 - 5000 Q\ R, + R, = —
' ^ P
C.|Ri-R2l = 50O D P<Y^
Cau 100: (De thi d^i hpc n5m nSm 2009) Ddt mpt di?n dp xoay chieu c6
gid tri hi?u dyng U vdo hai ddu doan m^ch AB gom cupn cam thuan c6 dp
tvr cam L, di?n tra thu^ R vd t\ di?n c6 di?n dung C mdc noi tilp theo thir
tir tren Gpi UL, UR vd Ucjan lupt Id cdc di?n dp hi?u d\mg giua hai dau moi
phan tu Diet di^n dp gifta hai dau doan m^ch AB Ifch pha ^ so v<5ri dien dp
no
VAT li K - T 6 M T A T iV THBYgl V A BAI T A P T B A C llBHigH - T A P 1 CBIflftiS 3: P f B BigB M A Y CHlgfl
giUa hai ddu doan mach NB (doan mach NB g6m R va C) H? thurc nao dual day la dung?
phan tu R vd L) l?ch pha ^ so voi URC (di?n dp tuc thai a hai dau R vd C)
i|hi R bang bao nhieu?
A.R = 300Q B.R=100n
C.R=100V2Q D.R = 200n
Cau 102: Cho m?ich di?n AB g6m mpt cupn cdm thuan L, mpt tu di?n C vd mpt di?n trd boat dpng R = 500 (theo thijr ty d6) mdc noi tilp voi nhau Khi
dat vdo A, B mpt dien dp xoay chieu M = 120V2cos(120;rO(V) thi dien dp
giua hai dau mach AM (m^ich AM chiia L va C) l$ch pha — so voi u Cuong dp dong di?n qua mach c6 gid tri hi?u dyng bdng
A 1,2A B 1,5A C.0,6A D
2,4A-Cau 103: lin lupt dat cdc di?n ap xoay chilu M,
W2=C/V2cos(120;rf+^2) vd MJ =f/-N/2cos(110;rt+^) vdo hai dau doan
I mach gom di?n tra thuan R, cupn cdm thuan c6 dp ty cdm L va ty di?n
I CO di?n dung C mSc n6i tiep thi cuong dp dong di?n trong dogn m?ich c6
bilu thuc tuang umg Id: i, = /V2cos(100;r0; i2 = Iyf2cosi\20;tt+~) va
is =/'>/2 cos(l 1 0 ; r r So sdnh I va r, ta c6:
A.I = r B.I=/'>/2 C K F D.I>F
179
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• CAC DVNG CV DIEN
Cau 104: Chon cau diing Nguyen tic hoat dpng cua may phat dien xoay
chieu mot pha, may phat dien xoay chieu ba pha, dong ca khong dong bo ba
pha, may bien ap dya tren:
A Viec su diang tu tmcmg quay
B Hien tugng cam ling di?n tir va sir dung tir truofng quay
C Hien tugng cam ung di?n tu
D Hien tugng tu cam
Cau 105: Roto cua may phat dien xoay chieu c6 5 cjp cue, quay vai toe do
720 vong/phut TSn s6 cua suk dien dong la
A.50HZ B lOOHz C.60Hz D 120Hz
Cau 106: Roto cua may phat dien xoay chi6u c6 5 cap cue, tan so cua dong
dien la 50Hz T6C dg quay cua roto la
A 12v6ng/s B.10v6ng/s C 20v6ng/s D 24v6ng/s
Cau 107: Trong cac cau sau day, cau nao sai?
A May phat di$n xoay chieu hoat dgng dya tren hi^n tugng cam
ling difn tu
B May phat di?n la thiet bi bien d6i ca nSng thanh dien nSng
C Moi may phat di?n deu c6 hai bg phan chinh la phan cam va
phan tao ra tu truang
D Mgt trong cac each tao ra suat di?n dgng cam ung trong may
phat dien la tao ra tir truang quay va cdc vong day dSt c6 dinh
Cau 108: So v6ng tren cugn sa cap va cugn thii cSp Ian lugt la 300 vong va
2400 vong Khi may hoat dgng, neu dong di§n chay trong cugn sa cSp la 18A
thi dong dien chay trong cugn thii cSp la: (bo qua sy hao phi dif n nSng)
A 2,25A B 144A C 5A D 14,4A
Cau 109: Mgt may t§ng the ly tuong c6 ti s6 vong day giiSa cac cugn sa cap
Ni va thu cap N2 la 3 Bik cuong dg dong dien trong cugn sa ckp vk hi?u
dien the hi?u dung giura hai dhi cugn sa c^p \hn lugt la Ii = 6 A v^ Ui = 120
V Cuong dg dong di?n hi?u dyng trong cugn thu dp va hifu di?n the hi?u
dung giiia hai dau cugn thu cap ihn lugt la
A.2Ava360V B 18 V va 360 V
C.2Av^40V D 18Av^40V
LY 1 2 - TdM TAT lY THUYfT VA BAI TAP TBAC WGHlgM - TAP 1 CHlTdNG 3: DdNG DllN XOAY GHI^U
Cau 110: Dieu nao sau day la khong dung khi noi ve dong di^n xoay chigu
ba pha?
A Cac dong dien xoay chi^u trong he thong dong dien xoay chieu
ba pha phai dugc tao ra tir ba may phat dien xoay chigu mgt pha
B Dong dien xoay chieu ba pha c6 cac dong di?n xoay chieu mgt pha lech pha nhau goc ^ «
C Moi dong dien xoay chieu trong h? th6ng dong di?n xoay chieu
ba pha dhu c6 cung bien dg, cung tan s6
D Dong dien xoay chi^u ba pha la h? thdng ba dong di?n xoay
chieu mgt pha
Cau 111: Phat bilu nao sau day la khong dung khi noi ve ciu tao va
nguyen tic hoat dgng cua may phat di?n xoay chilu ba pha?
A May phat di?n xoay chieu ba pha hoat dgng dya tren hien tugng cam ung dien tir
B Stato gom ba cugn day gi6ng nhau, b6 tri l$ch nhau 120° tren
Cau 112; Chgn cau sai
A Dgng co khong dong bg ba pha bien di?n naiig thanh co nang
B Dgng co khong d6ng bg ba pha ho^t dgng dya tren co so cua
hien tugng cam ung di?n tir va su dung tir truang quay
C V$n toe goc cua khung day luon nho hon van toe goc cua tir truang quay
D Dgng co khong dong bg ba pha tao ra dong dien xoay chilu ba pha
au 113: Trong dgng co khong dong bg ba pha, tir truang quay dugc tao ra
ig each:
A Cho ba dong dien mgt pha vao ba cugn day
1111
Trang 6C W l M M S 3 :Dtll8PlgimYCmg l W*T I t K - Ti m TAT LY THDYgT VA BAI TAP TRAC leHlgM - T A H
B Dung dpng ca dk quay mpt nam cham hinh chu: U ben trong
dpng ca
C Cho ba dong dien mpt pha vao mot cuon day
D Cho dong di?n ba pha vao ba cuon day gi6ng nhau dugc bo tri
lech nhau 1/3 vong tron
Cau 114: Ve cau tao, stato cua dong ca khong d6ng bo ba pha gom:
A Ba nam cham vTnh cuu bo tri lech nhau 1/3 vong tron
B Ba cuon day gi6ng nhau q u ^ tren ba loi sit b6 tri lech nhau
1/3 vong tron
C Ba nam cham di?n bo tri lech nhau 1/3 vong tron
D Ba cuon day giong nhau quan tren ba loi sit b6 tri lech nhau
1/3 vong tron va mic n6i ti6p vai nhau
Cau 115: Trong cac cau sau day, cau nao sai khi noi \h may bien ap:
A K h i may giam thS boat dong thi di?n ap hai dau cuon sa cip
Ion han dien dp hai dau cupn thu cap
B T i s6 giiia hi?u di?n the hi?u d\mg cua cupn thu cdp va cugn so
cap Cling la ti so so vong day cua chung
C Goi U i , I i , U2, h Ian lugrt la dien ap va cuong do dong
di?n hieu dving trong cupn sa cap va thu c i p thi ta luon c6
U , I,=U2l2
D May b i l n ap la thiSt bi hoat dpng dua tren hien tugng cam ung
dien tir, dung de tang hoac giam dien ap
Cau 116: Chon cau dung Gpi N i la so vong day cua cuon sa cap, N2 la s6
vong day cupn thur c i p va N i < N2 May bien the nay c6 tac dimg:
A Tang cuong dp dong di?n, giam hi?u dien thS
B Giam cuong dp dong di?n, tang hi?u di?n t h i
C Tang cucmg dp dong di?n, tang hi?u di?n the
D Giam cuong dp dong dien, giam hieu dien the
Cau 117: Chpn cau diing Trong qua trinh truy6n tai di§n nang, may bien
the CO vai tro:
A Giam di?n tra cua day dan
B Tang hi?u di?n the truyen tai de giam hao phi trong qua trinh
truyen tai
lY tt - m TAT Lf TWYgT WA l A l TAP T I A C tm» - TAP 1 CUd»6 8 : D t M Diew KOAY CHlgB
C G i ^ hi?u di?n thS truyen tai dk gidm hao phi trong qua trinh
truyen tai
D Tang cong suat truyen tai
[pau 118: Chpn cau sai Trong mpt may bien the, neu b6 qua hao phi di?n
ag cua cac cupn sa cap \h thur cap thi:
A May bien the 1 ^ ^ g hi?u di?n t h i bao nhieu \m thi cuong dp
dong di?n giam bay nhieu ISn va nguoc lai
B May ha t h i c6 tac dving lam tang cu6mg dp dong dien a mach
thii cip
C NSu s6 von^ day cupn thur cap Ian hem so vong day cupn sa cap
thi may bien the d6 gpi la may tang thg
D Di?n ap lay ra tang bao nhieu Ian so vai di?n ap dua vao thi cong suit ciing tang bay nhieu l i n
Cau 119: Trong qua trinh t r u y k tai di?n nang Hieu s6 chi cua cong ta di?n
a tram phat va a nod thu sau m6i ngay dem chenh l?ch nhau 480KWh Cong
suit hao phi dpc ducmg la ?
A.20kW B.40kW C 83kW D lOOkW Cau 120: Mpt dpng ca khong dong bp 3 pha c6 cong suit 3960W dupe mic
hinh sao vao mang di?n xoay chieu ba pha c6 hieu di?n thS gifta hai day pha
la 190V, he s6 cong suit dpng co bang 0,8 Cucmg dp dong dien hi?u dung chay qua tung cupn day cua dpng ca la
A lOA B 12A C 15A D 20A
I
183
Trang 7CHinrNG 8: DdMG mtn XOAY CHlgP V A T 11? « - TiU T A T LY THBYfT V A BAI T A P T B A C W E H I E M - T A P 1
DAP AN BAI TAP VA C A C C A U HOI TRAC
Cau 1 : Tir thong cue dai: (^Q = NBS = 0,54Wb
Cau3:co = 3000 vong/phiit = 3000x — = 100;irad/s;
60
- Eo = NBSco = 40,2V
Cau 4: Suat dien dong eirc dai: EQ = ^QCO = 2V
Cau 5: Bieu thuc suit dien dong: e = = 2 sin (lOO;it + ^) (V)
(Thai gian ng^n nhat vat dao dong tir vi tri x = + A den v i tri
A „ ' ' "
x = + - l a - )
i = lA = lo=>t = l:i = '-^ = 0,5A
184
VAT lY 12 - TdM T A T LY T H U Y £ T V A BAI T A P T B A C MEHlgW - T A P 1
Cau 14: 100V2 = U^f2 cos ( I O O T T 0 + | ) => [/ = 200K
Trang 8CHi/dH6 3: DdiiB mtn XBAY mt» m ly n - liu TAT I Y THOYgj vA BAI TAP TBAC IIBIUEM - TAP I
• Doan mach chi c6 cac di?n tra thuSn mSc noi tiep, tuang
duomg vai doan mach chi c6 mot dien tra thu§n duy nhSt vai
dien tra bang tong cac dien tra thuSn R = Ri + R2
• /oi = /02 = = 2V2 (A) -> Cau D sai
Cau 4: Mach chi c6 R u cung pha vai i
i = Y = V2 cos (lOOTTt -1) (A)
— - - = -4= cos(cot) — 7 = cos(a)t) = 0 -> Cau C dung
• + 4- = 2cos' (wt) -> Cau D sai
• Zi, = L6J = lOOQ; Io= — = 2,2V2A
Mach chi c6 L => u sam pha - so vai
i=>(Pi= i = 2,2V2 cos (lOOrrt -1) {A)
Trang 9CHI/dNG 3: DdNG OICN XOAY CHlf U VAT LY 1 2 - TiM TAT lY THUYfT VA BAI T A P THAC WeHieilll - T A P 1
Cau 13:
• Doan mach chi c6 C ==> i som pha hon u mot goc ^ ~
• Cuong do dong dien cue dai: /Q = — = UQCO)
• Bieu thuc cuong do dong dien: t = t/oCw cos {oit +
Cau 14:
Z C = ^ : = 1 0 0 Q ; I O = H L = 2,2V2A Ceo
• Mach dien chi c6 tu C, dong dien i som pha hon dien ap mot
• BiSu thurc cucmg do dong dien: i = 2,2V2 cos (lOOTit +1) (^4)
Cau 20: U = ^U^ + {Ui - UcY = 40V
Cau 22: tancp = ^ = -l=>(p = -^=>i s&m pha ^ so vai u
lY 1Z - TdM TAT l« THBYfT VA BAI T A P TBAC WGHIEM - T A P 1 CHlfflHB 8: DflNE D | £ N XOAY CHlgU Cau 24: Cac dap an A, B va D deu sai khi xet vg pha giua dong di$n
va dien dp Cau 26:
Suy ra, i tre pha - so vai u
Cau 31: <p = (^u - <Pi = - f < 0 t""*? < 0 => Z^ < Zc
Trang 10caiWM a: rtro mt» K I » T cwgy V > T t t « - it» TA T LT TBBYgi vA BAI T* P T B A C M H I £ H - T A P I
Trang 11CHtfir«e3:DI>«6 0lgl«XDAYCHlgB V<T tY IZ - TIJM T/JT LY T H B Y £ T V A BAI T A P T B A C HEHlgM - T A P 1
U,=^/3U,;coscp=^ = ^ ^ = ^
U 2U, 2
Caull: P = I^R = 'IR = SW
Cau 12: A = Pt = lOOOWh = lA:iy/i
• Uci = 2Uc2 => I i = 2I2 =J> Z2 = 2Zi
• t/«2 = 2(/«i /2«2 = 2/i/?i => /?2 = 4/?i (2)
Dap an B C D D B Cau 2:
Cau 4:
Thay doi C de Pmax mach cong huong
Z,=Zc=^U, = Uc = 2U
u cung pha voi U R u ciing pha voi i mach cong huong
Tan so cua dong di?n kjii mach xay ra hien tugng cpng huong:
1
f = = 25011/
27t>/LC
Cau 5: Zi = ZQ ^Mach cong hugng: U R = U
Cau 6: - 220V = U => mach cong huong
Cau 11: Thay doi w dk Pmax=> m?ch cpng huong: Pmax = ^ = 484U^