Gv: Nguyn Hng Khnh _ HKP PHNG PHP GII BI TP DNG IN XOAY CHIU LTHDi ng: 09166.01248 Email: Khanhcaphe@gmail.com Gio Dc Hng Phc - Ni Khi u c M! HP 1 CHNG IV: DNG IN XOAY CHIU BI 1: I CNG DNG IN XOAY CHIU. I. PHNG PHP. 1. GII THIU V DNG IN XOAY CHIU. A.nh ngha: Dng in xoay chiu l dng din c cng bin thin iu ha theo thi gian B.Phng trnh

i = I o.cos( et + ) ( A)Hoc u = U o.cos( et + ) (V)

Trong :- i: gi l cng dng in tc thi ( A) - I o: gi l cng dng in cc i ( A) - u: gi l hiu in th tc thi (V) - U o: gi l hiu in th cc i ( V) - e : gi l tn s gc ca dng in ( rad/s) C. Cc gi tr hiu dng: - Cng dng in hiu dng: I = I o2(A) - Hiu in th hiu dung: U = U o2(V) - Cc thng s ca cc thit b in thng l gi tr hiu dng - o cc gi tr hiu dng ngi ta dng vn k nhit, am pe k nhit... CC BI TON CN CH : Bi ton 1: Xc nh s ln dng in i chiu trong 1s: -Trong mt chu k dng in i chiu 2 ln -Xc nh s chu k dng in thc hin c trong mt giy ( tn s) S ln dng in i chiu trong mt giy: n = 2f Ch : Nu bi yu cu xc nh s ln i chiu ca dng in trong 1s u tin th n = 2f. -Nhng vi trng hp c bit khi pha ban u ca dng in l = 0 hoc th trong chu k u tin dng in ch i chiu 1 ln: n = 2f - 1. Bi ton 2: Xc nh thi gian n sng -ti trong mt chu k t s = seTrong : s = 4 ocos o = |u|U o

t t = te=2t - se= T - t s Gi H l t l thi gian n sng v ti trong mt chu k: H = t st t= s t

Bi ton 3: Xc nh in lng chuyn qua mch trong khong thi gian t Cho mch in, c dng in chy trong mch theo phng trnh: i = I o cos( et + )( A). Trong khong thi gian t t 1n t 2 hy xc nh in lng chuyn qua mch. q = ]((t 1 t 2 I o cos( et + )dt 2.GII THIU V CC LINH KIN IN. Ni dungin tr T in Cun dy thun cm K hiu Tngtr( ) R =.lS Z C = 1eC Z L = eL c im-Chocdnginmtchiu v xoay chiu qua n nhng ta nhit - Ch cho dng in xoay chiu i qua- Ch cn ch dng in xoay chiu Cngthcnh lut I = UR; I o = U oR ; i = uRI = UZ l; I o = U oZ l

I = UZ C; I o = U oZ C

Cng sutP = I2 .R00 RC L Gv: Nguyn Hng Khnh _ HKP PHNG PHP GII BI TP DNG IN XOAY CHIU LTHDi ng: 09166.01248 Email: Khanhcaphe@gmail.com Gio Dc Hng Phc - Ni Khi u c M! HP 2 lch pha u - iu v i cng pha vi nhau u chm pha hn i gc t2u nhanh pha hn i gc t2 Phng trnh u = U o.cos( et + ) (V) i = I 0.cos( et + ) A u = U o.cos( et + ) (V) i = I 0.cos( et + t2) A u = U o.cos( et + ) (V) i = I 0.cos( et - t2) A Gin u -i u i u i u i 3. QUI TC GHP LINH KIN. McRZ LZ C Mc ni tip R = R 1 + R 2

Z L = Z L 1 + Z L 2

Z C = Z C 1 + Z C 2 Mc song song 1R = 1R 1+ 1R 2 R = R 1 . R 2R 1 + R 2 1Z L = 1Z L 1 + 1Z L 2 Z L =Z L 1. Z L 2Z L 1 + Z L 2 Z C = Z C 1. Z C 2Z C 1 + Z C 2 4. CNG THC C LP THI GIAN: Vi on mch ch c Choc ch c cun dy thun cm ( L ) ta c: ( iI o )2 + (uU o )2 = 1 II. BI TP MU: V d 1: Mt dng in xoay chiu c phng trnh dng in nh sau: i = 5cos( 100tt +t2 ) A. Hy xc nh gi tr hiu dng ca dng in trong mch? A. 5 AB. 52 AC. 2.5AC. 2,52 A Hng dn: [ ] p n C Ta c: I = I o2= 52= 2,52A Chn p n C V d 2:Mt vn k khung quay o c hiu in th ca mt on mch l 220 V. Gi tr trn l: A. Gi tr cc iB. Gi tr tc thiC. Gi tr hiu dngD. Gi tr trung bnh Hng dn: [ ] p n CGi tr ca my vn k khung quay o c l gi tr hiu dng. Chn p n CV d 3: Ti thi im t = 1,5s cng dng in trong mch c gi tr l i = 5A. Gi tr trn l gi tr: A. Gi tr cc iB. Gi tr tc thiC. Gi tr hiu dngD. Gi tr trung bnh Hng dn: [ ] p n B Cng dng in ca dng in ti t = 1,5 s l gi tr tc thi. Chn p n B V d 4: Bit i = I 0 cos( 100tt+ t/6) A. Tm thi im cng dng in c gi tr bng 0? A. t = 1/300 + k/100s (k = 0,1,2..)B. t = 1/300 + k/100s (k = 1,2..) C. t = 1/400 + k/100 s(k = 0,1,2..)D. t = 1/600 + k/100 (k = 0,1,2..) Hng dn: [ ] p n A Gv: Nguyn Hng Khnh _ HKP PHNG PHP GII BI TP DNG IN XOAY CHIU LTHDi ng: 09166.01248 Email: Khanhcaphe@gmail.com Gio Dc Hng Phc - Ni Khi u c M! HP 3 Khi i = 0 A 100tt+ t/6 =t2+ kt 100tt =t3+ kt t = 1300 + k100svi k( 0,1,2 )

t2

A - A -t2

0 V d 5: Dng in c biu thc i = 2cos 100tt A, trong mt giy dng in i chiu bo nhiu ln?A. 100 lnB. 50 lnC. 110 lnD. 90 ln Hng dn: [ ] p n A Trong 1chu k dng in i chiu 2 ln 1s dng in thc hin 50 chu k S ln i chiu l: 100 ln Chn p n A V d 5: Dng in c biu thc i = 2cos 100tt A, trong mt giy u tin dng in i chiu bo nhiu ln?A. 100 lnB. 50 lnC. 110 lnD. 99 ln Hng dn: [ ] p n D - Chu k u tin dng in i chiu mt ln -Tnh t cc chu k sau dng in i chiu 2 ln trong mt chu k S ln i chiu ca dng in trong mt giy u tin l: n = 2.f - 1 = 2.50 - 1 = 99 ln. Chn p n D V d 6:Mch in c gi tr hiu dng U = 220, tn s dng in l 50Hz, n ch sng khi | | u 1102 V. Hy tnh thi gian n sng trong mt chu k? A. 1/75sB. 1/50sC. 1/150sD. 1/100s Hng dn: [ ] p n A Ta c: cos o = uU o= 11022202= 12

o =t3

s = 4. o =4t3

t s = se = s2tf=4t3.2. t.f= 175 s Chn p n A 2202110 2- 2202 - 110 2n sng n sng

t3

V d 7: Mch in X ch c t in C, bit C = 10-4 t F, mc mch in trn vo mng in c phng trnh u = 1002 cos( 100tt +t6 ) V. Xc nh phng trnh dng in trong mch. A. i =2 cos( 100tt +2t3 ) A B. i =2 cos( 100tt + t6 ) A A- A0 Gv: Nguyn Hng Khnh _ HKP PHNG PHP GII BI TP DNG IN XOAY CHIU LTHDi ng: 09166.01248 Email: Khanhcaphe@gmail.com Gio Dc Hng Phc - Ni Khi u c M! HP 4 C. i =cos( 100tt +2t3 ) AD. i =cos( 100tt + t6 ) A Hng dn: [ ] p n A Phng trnh dng in c dng:i = I ocos( 100 tt +t6+t2 ) A Trong : I o = U oZ C U o = 1002 Z C = 1eC = 1. t100t.10-4 = 100 I o =1002100=2 A Phng trnh c dng: i =2 cos( 100tt +2t3 ) A Chn p n A V d 8: Mch in X ch c mt phn t c phng trnh dng in v hiu in th ln lt nh sau: i = 22 cos( 100tt +t6 ) A. v u = 2002 cos( 100tt +t6 ) V. Hy xc nh l phn t g? v ln l bao nhiu? A. Z L = 100 B. Z C = 100 C. R = 100 D. R = 1002Hng dn: [ ] p n C V u v i cng pha nn y l R, R = U oI o= 100 p n C V d 9: Mt on mch ch c L:L = 1t H mc vo mng inv c phng trnh i = 2cos( 100 tt +t6 ) A, hy vit phng trnh hiu in th hai u mch in? A. u L = 200 cos( 100tt +2t3 ) VB. u L = 200 cos( 100tt + t6 ) V C. u L = 2002 cos( 100tt +2t3 ) VD. u L = 200 2 cos( 100tt + t6 ) V Hng dn: [ ] p n A u L c dng: u = U oL cos( 100tt +t6+t2 ) V Trong : Z L = e.L = 100 t. 1t = 100 I o = 2 A U oL = I o.L = 2.100 = 200 V

u L = 200 cos( 100 tt +2t3 ) V. Chn p n A Cu 10 : Cho mt cun dy c in tr thun 40 O v c t cm 0,4/t (H). t vo hai u cun dy in p xoay chiu c biu thc: u = U0cos(100tt - t/2) (V). Khi t = 0,1 (s) dng in c gi tr2,75 2(A). Ga tr ca U0 lA. 220 (V)B. 110 2(V)C. 220 2(V)D. 440 2(V) Hng dn: [ ] p n B R = 40 ;Z L = e.L = 100t .0,4t= 40 . Z =R2 + Z L2 = 402 . Phng trnh i c dng: i = I o cos( 100tt- t) A. Ti t = 0,1si = I o cos( 0) =2,752 I o= - 2,752A. U o= 1102V p n B. Cu 11:Mt in tr thun R=100O, khi dng dng in c tn s 50Hz. Nu dng dng in c tn s 100Hz th in tr s A.Gim 2 ln B. Tng 2 lnC. Khng iD. Gim 1/2 ln Hng dn: [ ] p n C:

Ta c:R =.lS Suy ra R khng ph thuc vo tn s ca mch III. BI TP THC HNH. Gv: Nguyn Hng Khnh _ HKP PHNG PHP GII BI TP DNG IN XOAY CHIU LTHDi ng: 09166.01248 Email: Khanhcaphe@gmail.com Gio Dc Hng Phc - Ni Khi u c M! HP 5 Cu 1: Tm pht biu ng v dng in xoay chiu? A: Dng in xoay chiu l dng in c tn s bin thin theo thi gian B:Dng in xoay chiu l dng in chiu bin thin iu ha theo thi gian C: Dng in xoay chiu l dng in c chiu bin thin tun hon theo thi gian D: Dng in xoay chiu l dng in ly ra t bnh c quy. Cu 2: Gi tr hiu dng ca dng in c xy dng trn c s A: Gi tr trung bnh ca dng inC: Kh nng ta nhit so vi dng in mt chiu B:Mt na gi tr cc iD: Hiu ca tn s v gi tr cc i Cu 3: Tm pht biu sai? A: Phn t R khi cho dng in i qua s ta nhit B:T in khng cho dng in mt chiu i qua C: Cun dy khng c chc nng ngn cn vi dng in xoay chiu D: T in cho dng in xoay chiu i qua nhng cn tr n Cu 4: Chn pht biu sai? A: Khi tng tn s s lm gi tr R khng iC: Khi tng tn s s lm in dung gim B:Khi tng tn s s lm cm khng tng theoD: Khi gim tn s s lm dung khng tng Cu 5: Tm pht biu ng? A: Dung khng c n v l FaraC: t cm c n v l B:Cm khng c n v l HenriD: in dung c n v l FaraCu 6: i vi dng in xoay chiu cch pht biu no sau y l ng? A: Trong cng nghip, c th dng dng in xoay chiu m in. B: in lng chuyn qua mt tit din thng dy dn trong mt chu k bng khng. C: in lng chuyn qua mt tit din thng dy dn trong khong thi gian bt k u bng khng. D: Cng sut to nhit tc thi c gi tr cc i bng 2ln cng sut ta nhit trung bnh. Cu 7: Trong cc i lng c trng cho dng in xoay chiu sau y, i lng no c dng gi tr hiu dng : A: Hiu in thB: Chu kC: Tn sD: Cng sutCu 8: Trong cc i lng c trng cho dng in xoay chiu sau y, i lng no khng dng gi tr hiu dng : A: Hiu in thB: Cng dng inC: Tn sD: Cng dng inCu 9: Pht biu no sau y l ng?A: Khi nim cng dng in hiu dng c xy dng da vo tc dng ha hc ca dng in. B: Khi nim cng dng in hiu dng c xy dng da vo tc dng nhit ca dng in. C: Khi nim cng dng in hiu dng c xy dng da vo tc dng t ca dng in. D: Khi nim cng dng in hiu dng c xy dng da vo tc dngpht quang ca dng in. Cu 10:Chn cu tr li sai. Dng in xoay chiu: A.gy ra tc dng nhit trn in trB:gy ra t trng bin thinC:c dng m in, c in D: bt buc phi c cng tc thi bin i theo thiCu 11:Trong tc dng ca dng in xoay chiu, tc dng khng ph thuc vo chiu ca dng in l tc dng: A:Nhit B:Ho C:TD:C A v B u ngCu 12:Trng hp no di y c th dng ng thi c hai lai dng in xoay chiu v dng in khng i: A:m din, c in. B:Np in cho acquy.C:Tinh ch kim lai bng in phn. D:Bp in, n dy tc Cu 13:Cng hiu dng I ca dng in xoay chiuA:L cng ca mt dng in khng i khi cho n i qua in tr R trong thi gian t th ta ra nhit lng Q = RI2tB: L gi tr trung bnh ca cng tc thi ca dng in xoay chiuC:C gi tr cng ln th tc dng nhit ca dng in xoay chiu cng lnD:C A,B,C u ngCu 14:Pht biu no sau y l khng ng?A: Hiu in th bin i theo thi gian gi l hiu in th xoay chiu. B: Dng in c cng bin i iu ha theo thi gian gi l dng in xoay chiu. C: Sut in ng bin i iu ha theo thi gian gi l sut in ng xoay chiu. D: Cho dng in mt chiu v dng in xoay chiu ln lt i qua cng mt in tr th chng ta ra nhit lng nh nhau. Cu 15:Khi cho dng in xoay chiu c biu thc i = I0cost (A) qua mch in ch c t in th ht tc thi gia hai cc t in: A.Nhanh pha i vi i.B:C th nhanh pha hay chm pha i vi i ty theo gi tr in dung C. C:Nhanh pha /2 i vi i. D:Chm pha /2 i vi i.Gv: Nguyn Hng Khnh _ HKP PHNG PHP GII BI TP DNG IN XOAY CHIU LTHDi ng: 09166.01248 Email: Khanhcaphe@gmail.com Gio Dc Hng Phc - Ni Khi u c M! HP 6 Cu 16:i vi dng in xoay chiu, kh nng cn tr dng in ca t in C: A: Cng ln, khi tn s f cng ln. B:Cng nh, khi chu k T cng ln.C:Cng nh, khi cng cng ln. D:Cng nh, khi in dung ca t C cng ln.Cu 17:Khi mc mt t in vo mng in xoay chiu, nu tn s ca dng in xoay chiu: A:Cng nh, th dng in cng d i quaB:Cng ln, dng in cng kh i quaC:Cng ln, dng in cng d i quaD:Bng 0, dng in cng d i quaCu 18:i vi dng in xoay chiu, cun cm c tc dng cn tr dng in: A:Dng in c tn s cng nh cng b cn tr nhiu. B: Dng in c tn s cng ln cng t b cn tr. C:Hon ton. D:Cn tr dng in, dng in c tn s cng ln cng b cn tr nhiu. Cu 19:Khi t vo hai u mt ng dy c in tr thun khng ng k mt ht xoay chiu th dng in tc thi i qua ng dy: A:nhanh pha /2 i vi u. B:chm pha /2 i vi u. C:cng pha vi u. D:nhanh hay chm pha i vi u ty theo gi tr ca t cm L ca ng dy.Cu 20:Khi tn s dng in xoay chiu chy qua on mch ch cha t in tng ln 4 ln th dung khng ca t inA. tng ln 2 lnB: tng ln 4 lnC: gim i 2 lnD: gim i 4 ln Cu 21:Khi tn s dng in xoay chiu chy qua on mch ch cha cun cm tng ln 4 ln th cm khng ca cun cmA: tng ln 2 lnB: tng ln 4 lnC: gim i 2 lnD: gim i 4 ln Cu 22:Cch pht biu no sau y l khng ng?A: Trong on mch ch cha t in, dng in bin thin sm pha t/2 so vi hiu in th. B: Trong on mch ch cha t in, dng in bin thin nhanh pha t/2 so vi hiu in th. C: Trong on mch ch cha cun cm, dng in bin thin chm pha t/2 so vi hiu in th. D: Trong on mch ch cha cun cm, dng in bin thin sm pha t/2 so vi hiu in th. Cu 23:Cho dng in xoay chiu hnh sin qua mch in ch c in tr thun th hiu in th tc thi gia hai u in trA: Chm pha i vi dng in. B: Nhanh pha i vi dng in. C:Cng pha vi dng in D:Lch pha i vi dng in /2. Cu 24:Pht biu no sau y l ng vi mch in xoay chiu ch cha t in? A: Dng in sm pha hn hiu in th mt gc t/2 B: Dng in sm pha hn hiu in th mt gc t/4 C: Dng in tr pha hn hiu in th mt gc t/2D: Dng in tr pha hn hiu in th mt gc t/4 Cu 25:Mt in tr thun R mc vo mch in xoay chiu tn s 50Hz, mun dng in trong mch sm pha hn hiu in th gia hai u on mch mt gc t/2 A: Ngi ta phi mc thm vo mch mt t in ni tip vi in tr B: Ngi ta phi mc thm vo mch mt cun cm ni tip vi in tr C: Ngi ta phi thay in tr ni trn bng mt t in D: Ngi ta phi thay in tr ni trn bng mt cun cmCu 26:Ht gia hai u on mch c biu thc: u = 2202cos 100t (V).Ht hiu dng ca on mch l: A:110 V B:1102 V C:220 V D:2202 VCu 27:Hiu in th hiu dng ca mng in dn dng bng 220V. Gi tr bin ca hiu in th bng bao nhiu? A: 156VB:380V C:311,12VD:440V Cu 28:Pht biu no sau y l sai khi ni v hiu in th hiu dng? A:c ghi trn cc thit b s dng in.B:c o bng vn k xoay chiu . C:c gi tr bng gi tr cc i chia 2.D:C A,B,C u sai Cu 29:Ngun xoay chiu c ht u = 1002cos100t (V). thit b hot ng tt nht th gi tr nh mc ca thit b l: A:100V B:1002V C:200 VD:2002V Cu 30:Cng ca mt dng in xoay chiu c biu thc: i = 4cos(100t - /2) (A). Gi tri hiu dng ca dng in l: A:2A B:22A C:4AD:42ACu 31:Mt dng in xoay chiu c cng i = 22cos(100t + /2) (A). Chn cu pht biu sai: A: Cng hiu dng I = 2A. B:f = 50Hz. C:Ti thi im t = 0,15s cng dng in cc i. D: = /2. Cu 32: Cng dng in trong mch khng phn nhnh c dng i=2 2 cos100tt(A). Cng dng in hiu dng trong mch l : A: I=4AB: I=2,83AC: I=2AD: I=1,41A Gv: Nguyn Hng Khnh _ HKP PHNG PHP GII BI TP DNG IN XOAY CHIU LTHDi ng: 09166.01248 Email: Khanhcaphe@gmail.com Gio Dc Hng Phc - Ni Khi u c M! HP 7 Cu 33:Hiu in th gia hai u on mch c dng u=141cos100tt(V). Hiu in th hiu dng gia hai u on mch l :A: U=141VB. U=50HzC: U=100VD: U=200V Cu 34: in p hai u bng n c biu thc u = 1002 cos100tt. n ch sng khi | | u 100V. Tnh t l thi gian n sng - ti trong mt chu k? A: 1/1B: 2/3C: 1/3D: 3/2 Cu 35:in p hai u bng n c biu thc u = 1002 cos100tt. n ch sng khi | | u 100V. tnh thi gian n sng trong mt chu k? A. t = 1/100sB: 1/50sC: t = 1/150sD:1/75s Cu 36: in p hai u bng n c biu thc u = 1002 cos100tt. n ch sng khi | | u 100V. Tnh thi gian n sng trong mt pht? A: 30sB: 35sC: 40sD: 45s Cu 37:Mch in c gi tr hiu dng U = 220, tn s dng in l 50Hz, n ch sang khi | | u 1102 V.Tnh t l thi gian n sng ti trong mt chu k? A: 1:1B. 1:2C: 2:1D: 3:2 Cu 38: Mt bng n in ch sng khi c | | u > 1002 V c gn vo mch in c gi tr hiu dng l 200 V, tm t l thi gian sng ti ca bng n trong mt chu k? A: 2:1B: 1:1C: 1:2D: 4:3 Cu 39:Mt bng n in ch sng khi c | | u > 1002 V c gn vo mch in c gi tr cc i l 200 V, tm t l thi gian sng ti ca bng n trong mt chu k? A: 3:1B: 1:2C: 2:1D: 1:1 Cu 40:Mt n ng c mc vo mng in xoay chiu tn s f = 50(Hz), U = 220(V). Bit rng n ch sng khi hiu in th gia hai cc ca n t gi tr u > 155(V). Trong mt chu k thi gian n sng l: A: 1100(s)B: 2100(s)C: 4300(s)D: 5100(s) Cu 41:t in p 0cos 1003u U t| |= |\ . (V) vo hai u mt cun cm thun c t cm 12 (H). thi im in p gia hai u t in l 150 V th cng dng in trong mch l 4A. Gi tr cng dng in hiu dng trong mch l A:4AB: 4 3 AC:2,5 2 AD: 5 A Cu 42:Dng vn k khung quay o in p xoay chiu th vn k o c: A: Khng o cB. Gi tr tc thiC. Gi tr cc iD. Gi tr hiu dng Cu 43:Mt bng n ng c mc vo mng in xoay chiu tn s f = 50 Hz. Bit rng n ch sng khi in p gia hai cc ca n t gi tru>110 2 V. Trong 2 s thi gian n sng l 4/3s. Xc nh in p hiu dng hai u bng n l A:220VB: 220 3 A C: 220 2 AD: 200 A Cu 44:Biu thc dng in trong mch c dng i = 4cos( 8tt + t/6)A, vo thi im t dng in bng 0,7A. hi sau 3s dng in c gi tr l bao nhiu? A: - 0,7AB: 0,7AC: 0,5AD: 0,75A Cu 45:Mt dng in c tn s 60Hz, hi trong mt s dng in i chiu bao nhiu ln? A: 100 lnB: 110 lnC: 150 lnD: 120 ln Cu 46:Cho dng in c biu thc i = 2cos( 100tt - t/3) A. Nhng thi im no ti cng tc thi c gi tr cc tiu? A. t = - 5/600 + k/100 s( k = 1,2..)B: 5/600 + k/100 s ( k = 0,1,2) C. 1/120 + k/100 s( k = 0,1,2)D: - 1/120 + k/100 s( k = 1,2) Cu 47: Cng dng in trong mch c biu thc i = 22 cos( 100tt + t/6) A. Vo thi im t cng c gi tr l 0,5A. hi sau 0,03s cng tc thi l bao nhiu? A: 0,5AB: 0,4AC: - 0,5AD: 1A Cu 48:Dng in xoay chiu c cng i 2cos(100 t)(A) = tchy qua mt on mch in. S ln dng in c ln 1(A) trong 1(s) l A: 200 lnB: 400 lnC: 100 lnD: 50 ln Cu 49:Cng dng in tc thi chy qua mt on mch in xoay chiu l( ) i=4cos 20t (A) , t o bng giy. Ti thi im t1 no dng in ang gim v c cng bng i2 = -2A. Hi n thi im( )2 1t = t +0,025 scng dng in bng bao nhiu ? A:2 3 A;B:-2 3 A;C: 2 A;D: -2 A; Gv: Nguyn Hng Khnh _ HKP PHNG PHP GII BI TP DNG IN XOAY CHIU LTHDi ng: 09166.01248 Email: Khanhcaphe@gmail.com Gio Dc Hng Phc - Ni Khi u c M! HP 8 Cu 50:Dng in xoay chiu chy qua mt on mch c biu thc2 2 os(100 )( ) i c t A = ,ttnh bng giy (s). Vo mt thi im no , dng in ang c cng tc thi bng2 2(A) th sau t nht l bao lu dng in c cng tc thi bng6(A)? A: 5(s)600.B: 1(s)600.C: 1(s)300.D: 2(s)300. Cu 51:Vi UR, UL, UC, uR, uL, uC l cc in p hiu dng v tc thi ca in tr thun R, cun thun cm L v t in C, I v i l cng dng in hiu dng v tc thi qua cc phn t . Biu thc sau y khng ng l: A: RUIR= B: RuiR= C: LLUIZ= D: LLuiZ=Cu 52:t in p xoay chiu u=U0coset vo hai u on mch ch c in tr thun. Gi U l in p hiu dng gia hai u mch; i, I0 v I ln lt l gi tr tc thi, gi tr cc i v gi tr hiu dng ca cng dng in trong on mch. H thc no sau y sai? A: 0 0U I0U I = .B: 0 0U I2U I+ = .C: u i0U I = .D: 2 22 20 0u i1U I+ = . Cu 53:Hai dng din xoay chiu c tn s ln lt l f1 = 50Hz, f2 = 100Hz. Trong cngmt khang thi gian s ln i chiu ca:A:Dng f1 gp 2 ln dng f2 B:Dng f1 gp 4 ln dng f2 C.Dng f2 gp 2 ln dng f1D:Dng f2 gp 4 ln dng f1 Cu 54:Bit i = I 0 cos( 100tt+ t/6) A. Tm thi im u tin cng dng in c gi tr bng cng dng in hiu dng k t thi im ban u? A:1/1200sB: 2/1200sC: 3/1200sD:2 /1200s Cu 55:Bit i = I 0 cos( 100tt+ t/6) A. Tm thi im cng dng in c gi tr cc i? A:t = -1/600 + k/100s ( k = 1,2,3..)B: t = -1/600 + k/100s ( k = 0,1,2,3..) C: t = -1/200 + k/100s ( k = 1,2,3..)D: t = -1/300 + k/100s ( k = 1,2,3..) Cu 56:Mch ch c R, u = 1002 cos( 100tt) V, R = 50 , tnh I 0 qua in tr?A: 32 AB: 2AC: 2,2AD: 22 A Cu 57:Mch in ch c R, biu thc i c dng i = 5cos100tt A, u = 202 cos 100tt V. tnh R? A: 4 B: 4/2 C: 42 D: 0,4 Cu 58: Mt t in c C = 10-3 /2t F mc vo ngun xoay chiu c in p u = 1202 cos100tt V. S ch Ampe k trong mch l bao nhiu? A: 4AB. 5AC: 6AD: 7A Cu 59:Mt mch inch c R, c u = 200cos 100tt V. R = 20 . Tnh cng sut trong mch l? A: 1000WB: 500WC: 1500WD: 1200W Cu 60:Trong mch ch c R, u v i lch pha bao nhiu? A: cng phaB: t/2 radC: - t/2 radD: t rad Cu 61:Mt t in c C = 10 F mc vo mch in xoay chiu c tn s 50Hz, tnh dung khng ca t? A: 31,8 B: 3,18 C: 0,318 D: 318,3 Cu 62:Mt cun dy c t cm L = 1/tH, mc vo dng in xoay chiu, trong mt pht dng in i chiu 6000 ln, tnh cm khng ca mch. A: 100 B: 200 C: 150 D: 50 Cu 63: Mt t in c C = 10-3 /2t F mc vo ngun xoay chiu c in p u = 141,2cos( 100tt - t/4) v. Cng dng in hiu dng trong mch c gi tr l? A: 7 AB: 6AC: 5AD: 4A Cu 64:Trong cc biu thc sau, biu thc no ng? A: R = u R /iB: Z L = u L/iC: Z C = u C/iD: p n khc Cu 65:Mch in c phn t duy nht( R,L hoc C) c biu thc u l: u = 402 cos100tt V, i = 22 cos(100tt + t/2)A. l phn t g?A: CB: LD: RD: C ba p n Cu 66: Mch in ch c mt phn t( R,L hoc C) mc vo mng in c hiu in th u = 2202 cos( 100tt)V, v c biu thc i l 22 cos100tt A. l phn t g? C gi tr l bao nhiu? A: R = 100 B: R = 110 C: L = 1/ tHD: khng c p n Cu 67: Mch in ch c C, bit C = 10-3 /2tF, tn s dao ng trong mch l 50 Hz. Nu gn on mch trn vo mng in c hiu in th u = 20cos( 100tt - t/6) V. Tnh cng sut ca mch? A: 100 WB: 50 WC: 40 WD: 0 W Cu 68:Mt m nc c in tr ca may so l 100 , c lp vo mng in 220 V - 50 Hz. Tnh nhit lng m nc ta ra trong vng 1 gi? A: 17424JB: 17424000JC: 1742400JD: 174240J Cu 69:Mt dng in xoay chiu c i = 50cos( 100tt - t/2) A.Gv: Nguyn Hng Khnh _ HKP PHNG PHP GII BI TP DNG IN XOAY CHIU LTHDi ng: 09166.01248 Email: Khanhcaphe@gmail.com Gio Dc Hng Phc - Ni Khi u c M! HP 9 -Tm thi im u tin k t thi im ban u dng in trong mch c gi tr bng 25 A?A: 1/200sB: 1/400sC: 1/300sD: 1/600s -Nu t in c C = 10-4 /t F th biu thc u ca hai u mch in l? A: 5000cos( 100tt) VB: 5000cos( 100tt - t) V C: 500cos( 100tt) VD: 500cos( 100tt - t) V Cu 70:Dng in trong mch c biu thc i = 2cos( 100tt + t/6) A v hiu in th trong mch c biu thc u = 200 cos( 100tt + 2t/3) V. Mch in trn cha phn t g? A: R = 100 B: L = 1/tHC: C = 10-4 /tFD: khng p nCu 71:Dng in trong mch c biu thc i = 2cos( 100tt + 2t/3) A v hiu in th trong mch c biu thc u = 200 cos( 100tt + t/6) V. Mch in trn cha phn t g? Tm gi tr ca n?A: R = 100 B: L = 1/tHC: C = 10-4 /tFD: khng p n Cu 72:Dng in trong mch c biu thc i = 2cos( 100tt + t/6) A v hiu in th trong mch c biu thc u = 200 cos( 100tt + t/6) V. Mch in trn cha phn t g?A: R = 100 B: L = 1/tHC: C = 10-4 /tFD: khng p n Cu 73: Mch in c hiu in th hiu dng U = 200 V, tm gi tr ca cng dng in khi mc ni tip R 1 = 20 v R 2 = 30 ? A: 4,4AB: 4,44AC: 4AD: 0,4A Cu 74:Mch in c hiu in th U = 200 V, tm gi tr ca cng dng in khi mc song song R 1 = 20 v R 2 = 30 ? A:1,667AB. 16,67AC: 166,7AD. 0,1667A Cu 75:Mch in c hiu in th hiu dngU = 200 V, tm gi tr ca cng dng in khi mc ni tip C 1 =10-3 /t F v C 2 = 10-3 /4tF. Bit f = 50Hz. A: 0,4AB: 0,04AC: 0,44AD: 4A Cu 76:Mch in c hiu in th U = 200 V, tm gi tr ca cng dng in khi mc song song C 1 = 10-3 /t F v C 2 = 10-3 /4t F. Bit f = 50Hz A: 8AB. 1,6AC: 25AD: 0,16A Cu 77:Mch in c hiu in th hiu dng U = 200 V, tm gi tr ca cng dng in khi mc ni tip L 1 =0,4 /t H v L 2 = 0,8/tF. Bit f = 50Hz A: 1,667AB: 16,67AC: 166,7AD: 0,1667A Cu 78:Mch in ch c R = 20 cmc vo ngun in c hin in th hiu dngU = 200 V. Tm cng sut trong mch? A: 2MWB: 2WC: 200WD: 2KW Cu 79:Mt mch in ch c mt phn t( R hoc L hoc C) nhng cha bit r l g? Nhng qua kho st thy dng in trong mch c biu thc i = 2 cos( 100tt + t/6) A, cn hiu in th c biu thc l u = 50 cos( 100tt + 2t/3) V. Vy l phn t g? A: R = 25 B: C = 10-3 /2,5 FC: L = 0,25/tHD: Khng p nCu 80:Mt mch in ch c mt phn t( R hoc L hoc C) nhng cha bit r l g? Nhng qua kho st thy dng in trong mch c biu thc i = 2 cos( 100tt + t/6) A, cn hiu in th c biu thc l u = 50 cos( 100tt - t/3) V. Vy l phn t g?A: R = 25 B: C = 10-3 /2,5t FC: L = 0,25/tHD: Khng p n Cu 81:Mt mch in ch c mt phn t( R hoc L hoc C) nhng cha bit r l g? Nhng qua kho st thy dng in trong mch c biu thc i = 2 cos( 100tt + t/6) A, cn hiu in th c biu thc l u = 50 cos( 100tt + t/6) V. Vy l phn t g? A: R = 25 B: C = 10-3 /2,5 FC: L = 0,25/tHD: Khng p n Cu 82:Mt dng in xoay chiu chy qua in tr R=10O, nhit lng ta ra trong 30min l 900kJ. Cng dng in cc i trong mch l :A: I0=0,22AB: I0=0,32AC: I0=7,07AD: I0=10,0A Cu 83:in tr ca mt bnh nu nc l R = 400. t vo hai u bnh mt ht xoay chiu, khi dng in qua bnh l i = 22cos100t(A). Sau 4 pht nc si. B qua mi mt mt nng lng. Nhit lng cung cp lm si nc l: A: 6400JB:576 kJ C:384 kJD:768 kJ Cu 84:Hai u cun thun cm L = 2/(H) c ht xoay chiuu = 1002cos(100t - /2)(V). Pha ban u ca cng dng in l: A:i = /2 B:i = 0 C: i = - /2D:i = - Cu 85:t vo hai u cun thun cm L mt ht xoay chiu U = 220V, f = 60Hz. Dng in i qua cun cm c cng 2,4A. cho dng in qua cun cm c cng l 7,2A th tn s ca dng in phi bng: A: 180Hz B: 120HzC: 60Hz D: 20Hz Cu 86:Mt cun dy L thun cm c ni vo mng in xoay chiu 127V, 50Hz. Dng in cc i qua n bng 10A. Khi : A:L = 0,04H B:L = 0,057H C:L = 0,08HD:L = 0,114HGv: Nguyn Hng Khnh _ HKP PHNG PHP GII BI TP DNG IN XOAY CHIU LTHDi ng: 09166.01248 Email: Khanhcaphe@gmail.com Gio Dc Hng Phc - Ni Khi u c M! HP 10 Cu 87:Gia hai cc ca mt t in c dung khng l 10 c duy tr mt ht c dng: u = 52cos100t (V) th i qua t in l: A:i = 0,52cos(100t + /2)(A)B: i = 0,52cos(100t - /2)(A) C: i = 0,52cos100t (A)D: i = 0,5cos(100t + /2)(A) Cu 88:Mach ch c R, biu thc i qua mch c dng i= 2cos 100tt A, R = 20 , vit biu thc u? A: u = 40 cos( 100tt + t/2) VB:u = 402 cos( 100tt + t/2) V C: u = 40 cos( 100tt ) VD: u = 402 cos( 100tt + t) V Cu 89:Mch in ch c cun cm, L = 1/t H, biu thc i c dng i = 2cos( 100tt)A. Tnh Z L, biu thc u? A: Z L = 100 ; u = 200cos( 100tt - t/2) VB: Z L = 100 ; u = 200cos( 100tt +t/2) V C: Z L = 100 ; u = 200cos( 100tt ) VD: Z L = 200 ; u = 200cos( 100tt + t/2) V Cu 90: Mch ch c C, i = 22 cos100tt A, C = 10-4 /tF. Vit phng trnh u? A: u = 2002 cos( 100tt + t/2) VB: u = 2002 cos( 100tt + t/2) V C: u = 200 cos( 100tt -t/2) VD: u = 2002 cos( 100tt - t/2) V Cu 91: Mch ch c C, C = 31,8F, u = 1002 cos100tt V, Vit phng trnh i? A: i =2 cos( 100tt + t/2) AB: i =2 cos( 100tt - t/2) A C: i = 2 2 cos( 100tt + t/2) AD: i = 2 2 cos( 100tt - t/2) A Cu 92: Mch ch c L = 0,5/tH, i = 42 cos( 100tt + t/6) A. Vit phng trnh u? A: u = 2002 cos( 100tt - 2t/3) VB:u = 200cos( 100tt - 2t/3) V C:u = 200cos( 100tt + 2t/3) VD:u = 2002 cos( 100tt + 2t/3) V Cu 93:Mch in gm cun dy thun cm, t cm L = 1/4tHc gn vo mng inxoay chiu ngi ta thy dng in trong mch c biu thc l i = 2 cos( 100tt - t/6) A. Hi nu gn vo mng in on mch ch c t in c in dung l 10-3 /2tF th dng in trong mch c biu thc l? A: i = 25cos( 100tt + t/2) A B: i = 2,5cos( 100tt + t/6) A C: i = 2,5 cos( 100tt + 5t/6) AD: i = 0,25 cos( 100tt + 5t/6) A Cu 94:Mch inc cundy thuncm t cml 0,4/tH c gnvomngin xoaychiucphngtrnhu = 100cos( 100tt - t/2) V. Vit phng trnh dng in qua mch khi ? V nu cng mng in ta thay cun dy bng in tr R = 20 th cng sut ta nhit trong mch l bao nhiu? A: i = 2,4cos( 100tt - t) A; P = 250WB: i = 2,5cos( 100tt - t) A; P = 250W C: i = 2cos( 100tt + t) A; P = 250WD: i = 2,5cos( 100tt - t) A; P = 62,5W Cu 95: Mc cun dy thun cm c t cm L = 1/t H th trong mch c dng in i = 52 cos( 100tt + t/3) A. Cn nu thay vo l mt in tr 50 th dng in trong mch c biu thc l g? A: i = 10 cos( 100tt + 5t/6) AB: i = 102 cos( 100tt + t/6) A C: i = 102 cos( 100tt - 5t/6) AD: i = 102 cos( 100tt + 5t/6) A Cu 96:t vo hai u cun thun cm L = 1/ (H) mt ht: u = 200cos(100 t + /3) (V). Biu thc ca cng dng in trong mch l: A:i = 2cos (100 t + /3) (A) B: i = 2cos (100 t + /6) (A) C:i = 2cos (100 t -/6) (A)D:i = 2 cos (100 t - /3 ) (A) Cu 97:Cho dng in i = 42sin100t (A) qua mt ng dy thun cm c L = 1/20(H) th ht gia hai u ng dy c dng: A:u = 202cos(100t + )(V) B: u = 202cos100t (V) C:u = 202cos(100t + /2)(V)D: u = 202cos(100t /2)(V)

Cu 98:Dng in xoay chiu chy qua mt on mch c biu thc c biu thc cng l ( )0i = I cos t -/2 , viI0 > 0. Tnh t lc t = 0(s), in lng chuyn qua tit din thng ca dy dn ca on mch trong thi gian bng na chu k ca dng in l:A: 0.I 2.B. 0.C. 0.I 2. D. 02I . Cu 99: Dng inxoaychiu quamt onmchc biu thc i =2cos(120t -) A3. inlngchuyn quamch trong khong thi gian T6 k t thi im t = 0 l A: 3,25.10-3 C.B: 4,03.10-3 C.C: 2,53.10-3 C.D: 3,05.10-3 C. Gv: Nguyn Hng Khnh _ HKP PHNG PHP GII BI TP DNG IN XOAY CHIU LTHDi ng: 09166.01248 Email: Khanhcaphe@gmail.com Gio Dc Hng Phc - Ni Khi u c M! HP 11 CHNG IV: DNG IN XOAY CHIU BI 2: MCH IN RLC I. PHNG PHP 1. GII THIU V MCH RLC Cho mch RLC nh hnh v:Gi s trong mch dng in c dng: i = I o cos( et + ) A U R = U oR cos( et) V; u L = U oL cos( et +t2) V; u C = U oC cos( et -t2 ) V Gi u l hiu in th tc thi hai u mch: u = u R + u L + u C

u =U oR cos( et)+ U oL cos( et +t2)+U oC cos( et -t2 ) (1) U o2 = U oR2 +( U o L - U oC )2 ( Chia hai v ca (1) cho2 ) U oR

U oCU o L

U o L - U oC U o

U2 = U R2 + ( U L - U C )2 (2) Gi l lch pha gia u v i ca mch in tan = U o L - U oC U oR=U L - U CU R

(3) H s cng sut ( cos ): cos = U oRU o =U RU 2.NH LUT I o = U oZ = U oRR = U oLZ L = U oCZ C I = UZ = U RR = U LZ L = U CZ C - V dng in trong mch l nh nhau ti mi im, ta chia hai v ca (1) cho I 0

Z = R2 + ( Z L - Z C )2 Trong : Z l Tng tr ca mch( )R l in tr ( )Z L l cm khng ( Z L )Z C l dung khng( Z C) - V dng in trong mch l nh nhau ti mi im, ta chia hai v ca (2) cho I 0

tan = Z L - Z C R

- V dng in trong mch l nh nhau ti mi im, ta chia hai v ca (3) cho I 0

cos = RZ

- Nu tan > 0 Z L > Z C ( mch c tnh cm khng) - Nu tan < 0 Z C > Z L ( mchh c tnh dung khng) - tan = 0 mch ang c hin tng cng hng in 3. CNG SUT MCHRLC- P(W) P = UI.cos = I2 .R U l hiu in th hiu dng ca mch ( V)I l cng dng in hiu dng ( A) cos l h s cng sut 4. CNG HNG IN Hin tng cng hng sy ra khi e dng in= e ring= 1LC

e2 = 1LC eL = 1eC Z L = Z C H qu ca cng hng: Z min = R ;I max = UR; i = uZ;tan = 0; = 0; cos = 1; P max= U.I; Bi ton ph: Mch RLC c f thay i c, khi f = f 1 ( e 1)v khi f = f 2( e 2 )th dng in trong mch, U R, cng sut trong mch l nh nhau. f2 = f 1.f 2hoc e2 =e 1. e 2th dng in trong mch l cc i, U R cc i, cng sut t cc i.

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Trng s trng hp c bit: - Vit phng trnh u L. u L = U o L .cos( et +t2 ) (V) Trong : U o L= I o. Z L - Vit phng trnh u C :u C = U o C . cos( et +t2 ) (V) Trong : U o C= I o. Z C - Vit phng trnh u R:u R = U o R . cos( et ) ( V) Trong : U o R = I o.RLoi 2: Vit phng trnh i khi bit phng trnh u. Cho on mch RLC, bit phng trnh hiu in th on mch X c dng: u X= U O.cos(et)(V) Phng trnh i s c dng: i = I Ocos( et - X ). (A)Trong : tan X= Z L X - Z CXR X

Mt s trng hp c bit:- Bit phng trnh u R = U OR cos( et + ) i = I Ocos(et + ) - Bit phng trnh u L = U OL cos( et + ) i = I Ocos(et + -t2 ) - Bit phng trnh u C = U OC cos( et + ) i = I Ocos( et + +t2) Loi 3: Vit phng trnh u Ykhi bit phng trnh u X. Mch in RLC c phng trnh u Ydng: u Y= U o Y .cos( et + ) (V). Hy vit phng trnh hiu in th hai u on mch X: Bc 1: Xy dng phng trnh i i = I o.cos( et + - Y) (A)Trong : tan Y= Z L Y - Z C YR Y ;I 0= U OYZ Y

Bc 2: Xy dng phng trnh hiu in th bi yu cu: u X= U o X.cos( et + - Y+ X )Trong :tan X= Z L X - Z CXR X; U OX= I 0. Z X II. BI TP MU: V d 1:Mch in xoay chiu RLC khng phn nhnh c: R = 50O; L = 107H;C = 2103 F. t vo hai u on mch mt in p xoay chiu c tn s 50 Hz th tng tr ca on mch A. 50 O. B. 50 2 O.C. 50 3 O.D.50 5Gii: Ta c: Z =R2 + (Z L - Z C)2

Z L = eL = 100t. 710t = 70 Z C = 1eC =1.2. t100t10-3 = 20 R = 50 Z =502 + ( 70 -20)2 = 502 p n B V d 2: Cho mch in gm in tr R =100O, cun dy thun cm L =1H, t in c C =12.10-4F . Hiu in th hai u on mch c tn s l 50 Hz. Pha ca hiu in th hai u on mch so vi hiu in th gia hai bn t l A. Nhanh hn 4B. Nhanh hn 2C. Nhanh hn 3D. Nhanh hn 34 Gii: Ta c:tan = Z L - Z C R

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Z L = eL = 100t. 1t = 100 Z C = 1eC =1.2t100t.10-4 = 200 R = 100 tan =100 - 200100= - 1 = -t4

i nhanh pha hn u gct4; i nhanh pha hn hiu in th hai u t lt2

u nhanh pha hn u Cgct4 p n A V d 3:Mt on mch gm cun dy c in tr thun 100 3O, c t cm L ni tip vi t in c in dung 0,00005/t (F). tvohaiuonmchmtinpxoaychiuu=U0cos(100tt-t/4)(V)thbiuthccngdnginquamchi= 2 cos(100tt - t/12) (A). Ga tr ca L l A. L = 0,4/t (H)B. L = 0,6/t (H)C. L = 1/t (H) D. L = 0,5/t (H)Gii: Ta c: i =2 cos(100tt - t/12) (A)u = U0cos(100tt - t/4) (V) = - t6 (rad) tan = Z L - Z C R= tan ( -t3 ) = - 13

Z L - Z C = - 100 Z C = 1eC=t 100t .0,00005= 200 Z L = 200 - 100 = 100 L = 1t H Chn p n C V d 4: t vo hai u on mch RLCin p xoay chiu .Bit rng ZL = 2ZC = 2R.A.in p lun nhanh pha hn cng dng in l6 B. in p lun tr pha hn cng dng in l 4 C.in p v cng dng in cng phaD.in p lun nhanh pha hn cng dng in l 4 Gii: V: ZL = 2ZC = 2R Z L = 2Z C R = Z C

tan = Z L - Z C R= 2Z C - Z CZ C= 1 =t4 ( u nhanh pha hn i gct4 ) Chn p n D V d 5:Mt mch R,L,C mc ni tip trong R = 120O, L = 2/ H v C = 2.10 - 4/ F, ngun c tn s f thay i c. i sm pha hn u, f cn tho mnA: f> 12,5HzB: fs 12,5Hz C. f< 12,5HzD. f < 25Hz Gii: i sm pha hn i Z C > Z L

12tfC> 2tfL f2 < 14t2 LC f 1D: kc tnh bi cng thc: k = cos = R/Z Cu 8: Chn cu tr li sai. Cng sut tiu th trong mch in xoay chiu gm R,L,C mc ni tipA:L cng sut tc thi B:LP = UIcos C:L P = RI2D:L cng sut trung bnh trong mt chu kCu 9: Mt on mch khng phn nhnh c dng in sm pha hn hiu in th mt gc nh hn/2 A:Trong on mch khng th c cun cm. B:H s cng sut ca on mch bng khngC:Nu tng tn s dng in ln mt lng nh th cng hiu dng qua on mch gimD:Nu tng tn s dng in ln mt lng nh th cng hiu dng qua on mch tngCu 10:Mt t in c in dung C = 5,3F mc ni tip vi in tr R = 300O thnh mt on. Mc on mch ny vo mng in xoay chiu 220V-50Hz. H s cng sut ca mch l : A: 0,3331B: 0,4469C: 0,4995D: 0,6662Cu 11:Mt t in c in dung C=5,3F mc ni tip vi in tr R=300O thnh mt on. Mc on mch ny vo mng in xoay chiu 220V-50Hz. in nng m on mch tiu th trong mt pht l :A: 32,22JB: 1047JC: 1933JD: 2148J Cu 12:Mt cun dy khi mc vo hiu in th xoay chiu 50V-50Hz th cng dng in qua cun dy l 0,2A v cng sut tiu th trn cun dy l 1,5W. H s cng sut ca mch l bao nhiu?A: k = 0,15B: k = 0,25C: k = 0,50D: k = 0,75 Cu 13:Ht hai u mch l: u = 100sin(100 t - /3) (V), dng in l: i = 4cos(100 t + /6) (A). Cng sut tiu th ca mch l: A:200WB:400W C:800WD:mt gi tr khc. Cu 14:Mt mch xoay chiu c u = 2002cos100t(V) v i = 52cos(100t + /2)(A). Cng sut tiu th ca mch l: A:0B:1000W C:2000WD:4000W Cu 15:Mch R,L,C ni tip: R = 50, L = 1/2(H), C = 10-4/(F), f = 50 Hz. H s cng sut ca an mch l: A:0,6B:0,5 C:1/2 D:1 Cu 16:Mch RLC mc ni tip c mc vo mng in xoay chiu c tn s khng i. Nu cun dy khng c in tr th h s cng sut cc i khi no?A: R = Z L - Z C B: R = Z L C: R = Z C D: Z L = Z C

Cu 17:Mch RLC c R thay i c c mc vo mng in xoay chiu c tn s khng thay i, R bng bao nhiu th mch t cng sut cc i?( Khng c hin tng cng hng xy ra). A: R = | | Z L - Z CB: Z L = 2Z CC: Z L = RD: Z C = RCu 18:Mch RLC mc ni tip, cun dy c in tr trong r. Khi R thayi th gi tr R l bao nhiu cng sut trong mch t cc i? ( Khng c hin tng cng hng xy ra). A: R = | | Z L - Z CB: R + r =| | Z L - Z C C: R - r =| | Z L - Z CD:R = 2 | | Z L - Z C Cu 19:Mch in ch c R = 20 , Hiu in th hai u mch in l 40 V, tm cng sut trong mch khi . A:40 WB: 60WC: 80WD: 0W Cu 20: Mch in ch c C, C = 10-4 /tF, tn s ca dng in trong mch 50 Hz, hiu in th hiu dng l 50 V. Tm cng sut trong mch khi . A: 40 WB: 60WC: 80WD: 0W Cu 21:Mch in ch c L, L = 1/t H, tn s ca dng in trong mch 50 Hz, hiu in th hiu dng l 50 V. Tm cng sut trong mch khi .Gv: Nguyn Hng Khnh _ HKP PHNG PHP GII BI TP DNG IN XOAY CHIU LTHDi ng: 09166.01248 Email: Khanhcaphe@gmail.com Gio Dc Hng Phc - Ni Khi u c M! HP 25 A: 40 WB: 60WC: 80WD: 0W Cu 22:Mch RLC mc ni tip c mc vo dng in xoay chiu c phng trnh hiu in thu = 2202 cos( 100tt + t/3) V v phng trnh dng in l i = 22 cos( 100tt + t/2) A. Tm cng sut ca mch in trn? A. 220WB: 440 WC: 2203 WC: 351,5W Cu 23:Mch RL cR = 50 , L = 1/tH c mc vo mng in xoay chiu c tn s trong mch l 50 Hz-Tnh tng tr trong mch khi A: Z = 50 B: 502 C: 503 D: 505 -Nu hiu in th hai u mch in l 50 V, Hy tnh cng sut trong mch khi . A: 20 WB. 10WC: 100WD: 25W Cu 24: Mch in c RC, bit R = 50 , C = 10-4 /tF. Mch in trn c gn vo mng in c hiu in th 50 V, tn s 50 Hz.-Tnh tng tr ca mach in? A:Z = 50 B: 502 C: 503 D: 505 - Cng sut trong mch khi . A: 20 WB: 10WC: 100WD: 25W Cu 25:Mch in RLC c C thay i, R = 50 , Z L = 50 ,Mc mch in trn vo mng in xoay chiu c tn s trong mch l 50 Hz,- Tm C cng sut trong mch t cc i. A: C = 10-4 5t FB: 10-3 5t FC: 1t FD: 0,5 tF -Bit U = 100V, hy tnh cng sut khi . A: 50WB: 60WC: 100WD: 200W Cu 26: Mch in LC bit L = 0,6/tH, C = 10-4 /tF c mc vo mch in c tn s trong mch l 50 Hz. Tnh tng tr ca mch? A: 100 B: 50 C: 40 D: 60 -Nu gi tr ca hiu in th hai u mch in lU = 50 V, tnh cng sut ca mch khi ?A: 200WB: 100WC: 600WD: khng p n ng - Cng mch in khi ta gn thm in tr 40 th cng sut trong mch l bao nhiu? A: 40WB: 31,25WC: 30WD: 0W Cu 27:Mch in RLC mc ni tip, gn mch in trn vo mng in xoay chiu c hiu in th 50 V. Bit L = 1/tH, C = 10-4 /tF.- Tnh f cng sut trong mch t cc i? A:60HzB: 40HzC:50HzD: 100Hz -Nu cng sut cc i trong mch 100 W. Hy tnh in tr ca mch?A: 20 B: 30 C: 25 D: 80 Cu 28:Mch in RLC c in thun R = 50 , L = 1/tF c mc vo mng in c tn s trong mch l 50 Hz,-Tm C cng sut trong mch t gi tr cc i? A: 31,8 nFB: 318FC: 31,8FD: 3,18F - Nu hiu in th hiu dng trong mch c gi tr l 100V, tm cng sut ca mch khi ? A: 50WB: 100WC: 200WD: 150W Cu 29:Mch in RLC c R thay i c. Z L = 100 , Z C = 60 c mc vo mch in xoay chiu50V - 50Hz. -Tm R cng sut trong mch t gi tr cc i? A. 30 B: 40 C: 50 D: 60 - R thay i mch in c cng sut cc i, Tnh gi tr h s cng sut khi ? A: cos = 1B: cos = 1/2 C: cos = 1/2 D:3 /2 - Tnh cng sut tiu th trong mch khi ? A: 30 WB: 31,25WC: 32WD: 21,35W Cu 30:Mt cun dy gm in tr R = 40 c mc vo mng in 40 V - 50Hz.- Tnh L cng sut trong mch t cc i? A: L tin n B: L tin v 40mHC: L =0,4t HD: L tin v 0 H. - Tnh cng sut khi ? A: 80WB: 20WC: 40WD: 60W Cu 31:Mch in gm c cun dy, in tr trong l 50 , t cm ca mch l 0,4/tH, Mc mch in trn vo mng in xoay chiu c tn s thay i c.- Tnh tn s dng in cng sut trong mch l cc tiu? A: f = 0 HzB: 50HzC: 100HzD: - Nu iu chnh tn s dng in trong mch n gi tr 50Hz sau mc thm vo mch in mt tu in. Hy tnh in dung ca t cng sut trong mch t cc i? A: 10-4 t FB: 4. 10-4 t FC: 10-3 4t FD: Khng c p n Gv: Nguyn Hng Khnh _ HKP PHNG PHP GII BI TP DNG IN XOAY CHIU LTHDi ng: 09166.01248 Email: Khanhcaphe@gmail.com Gio Dc Hng Phc - Ni Khi u c M! HP 26 Cu 32: Mch in c RLC mc ni tip, R = 300 , L = 2/tH, C = 10-4 /2tF. Mch in trn c mc vo mng in xoay chiu c hiu in th 100V v tn s c th thay i c.- Tm gi tr tn s dng in cng sut trong mch t cc i?A: 100HzB: 60HzC: 40HzD: 50 Hz - Tnh cng sut cc i trn? A: 33,0WB: 20WC: 200WD: 50W - Thay i tn s trong mch thnh 100 Hz hy tnh cng sut lc ny? A: 166,7WB. 16,67WC: 1,667WD: Khng p n. Cu 33:Mch in RLC mc ni tip c R thay i c. c t vo mch in 200V - 50Hz. Thy cng sut trong mch t cc i bng 100 W( Khng c hin tng cng hng), bit C = 10-3 / 2t F, hy tnh gi tr ca R? A: R = 50 B: 100 C: 200 D: 400 Cu 34:Mch RLC mc ni tip, trong R c th thay i c, cun dy c r = 20 , L = 1/tH, t in C = 10-3 /(5t) F. Gn mch in trn vo mng in xoay chiu c hiu in th 300V - 50 Hz. iu chnh R cng sut trong mch t cc i.- Hy tnh gi tr hiu in th gia hai u t in? A: 150 B: 1002 C: 1502 D: 300 - Tnh h s cng sut gia hai u cun dy? A: 0,15B: 0,2C: 0,5 D: 1/2Cu 35:Mch in c hai phn t RC c C thay i, c mc vo mng in xoay chiu c tn s 50 Hz,bit in tr trong mch l 60 , tnh C cng sut trong mch l ln nht? A: C tin v 0B: C tin v C: C tin v 10-3 /(6t)FD: Khng c p n-Nu U = 300V tnh cng sut ca mch khi ? A: 1000WB: 5100WC: 1500WD: 2000W Cu 36: Mch RLC mc ni tip c mc vo mng in c tn s thay i c.Bit in tr trongmch l 20 , L = 0,3/tH, C = 10-3 /3tF.- Tnh f cng sut trong mch t cc i? A: 100 HzB: 200 HzC: 150HzD: 50Hz -Bit hiu in th hiu dng trong mch l 100V. Tnh P? A: 50WB: 1000WC: 500WD: 5000W Cu 37: Mach RLC c R thay i c, trong : cun dy c r = 30 , L = 0,5/tH, C = 10-3 /tF, c gn vo mach in 220V - 50 Hz.- Phi iu chnh R n gi tr no cng sut trong mch t cc i?A: 100 B: 40 C: 20 D: 10 - Tnh cng sut trong trng hp ?A: 480 WB: 484 WC: 500WD: 510W - R bng bao nhiu cng sut trn in tr R ln nht? A: 10 B: 20 C: 50 D: 60 Cu 38:Trong mt chic qut in, cun dy c L = 0,1/tH, r = 5 , cm chic qut vo mng in 220V - 50 Hz.-Tnh cng sut ca chic qut?A. 2KWB: 1,9KWC: 1,936KWD: 1KW - tng cng sut ca chic qut ngi ta gn thm mt t in, Khi cng sut ca ng c t cc i hy xc nh gi tr ca C khi ? A: 10-4 /t FB: 10-3 /tFC: 10 FD: 1/10FCu 39:Mch RLC c R thay i c, C = 31,8 F, L = 2/tH, c mc vo mng in 200V - 50Hz. iu chnh R cng sut trong mch t cc i.-Tnh cng sut cc i ?A: 100WB: 400WC: 200WD: 250 W -Gi nguyn R v gn thm vo mch mt t in cng sut l ln nht. Tnh cng sut khi ? A: 100WB: 400WC: 200WD: 250 W Cu 40:Mch RLC c R thay i, khi R = 20 v khi R = 40 th cng sut trong mch l nh nhau. Tm R cng sut trong mch t cc i? A: R = 30 B: 202 C: 40 D: 69 Cu 41:Mach RLC khi tn s f = 50 Hz v khi f = 60 Hz th cng sut trong mch l nh nhau, tm f cng sut trong mch t cc i? A: 50 HzB: 55 HzC: 54,3HzD: 54,77Hz Cu 42: Mch RLC khi f = f 1 = 60 Hz v khi f = f 2 th cng sut trong mch l nh nhau. Khi f = 70 Hz th cng sut trong mch t cc i, tnh f 2.A: 81,67HzB: 90 HzC: 97HzD: 100hz Cu 43:Mch RLC c R thay i, ta thy khi R = 10 v khi R = 20 th cng sut trong mch l nh nhau. Tm gi tr ca R cng sut trong mch t cc i? A: 10 B: 15 C: 12,4 D: 102 Gv: Nguyn Hng Khnh _ HKP PHNG PHP GII BI TP DNG IN XOAY CHIU LTHDi ng: 09166.01248 Email: Khanhcaphe@gmail.com Gio Dc Hng Phc - Ni Khi u c M! HP 27 Cu 44:Mt mch xoay chiu gm mt cun cm c R = 30, L =1/4(H), mc ni tip vi mt t in c C = 10-4/(F). Ht hai u mch l u = 2502cos(2ft +/2) (V). iu chnh f cng dng in trong mch c gi tr cc i. Gi tr ca f khi l: A:25HzB:50HzC:100Hz D:200Hz Cu 45:Mch RLC c R thay i c, Bit L = 1/tH v mch in trn c gn vo mng in 220V -50Hz. Khi iu chnh R = 40 v khi R = 160 th cng sut trong mch l nh nhau. Tm gi tr ca dung khng? A: Z C = 200 B: Z C = 100 C: Z C = 20 D: 50 Cu 46:Chon cu sai: Cho mt on mch xoay chiu RLC ni tip. Bit L = 1/(H), C = 10-3/4(F). t vo hai u mch mt ht u =1202sin 100 t (V). Thay i R cng dng in hiu dng trong mch t cc i. Khi : A:dng in trong mch l Imax = 2A B:cng sut mch l P = 240 W C:in tr R = 0D: cng sut mch l P = 0. Cu 47:Mch RLC ni tip: R = 25; C = 10-3/5(F) v L l cun thun cm bin i c. Hiu in th gia hai u mch lu = 1002cos(100t + /4) (V).Thay i L sao cho cng sut mch t cc i. Gi tr ca L khi l: A:L = 1/2(H)B:L = 1/(H)C:L = 2/(H)D:L = 4/(H) Cu 48:MchR,L,Cmcnitip:R=80;r=20,L=2/(H),Cthayic.Hthaiuanmchl:u= 1202cos100t (V). Thay i C cng sut mch cc i. Gi tr cc i ca cng sut bng: A:Pmax = 180W B:Pmax = 144WC:Pmax = 288WD:Pmax = 720WCu 49:Mch RLC mc ni tip. Bit R= 100, L = 1/(H) v C thay i c. Hiu in th hai u mch c biu thc: u = 2002cos100t (V).Thay i C h s cng sut mch t cc i. Khi cng hiu dng trong mch bng: A:1A B:2A C:2 A D: 22ACu 50:Mch RLC ni tip. Bit R = 100, C =10-4/(F). Cun thun cm c L thay i c. Bit hiu in th gia hai u on mch l u = 200cos 100t (V). Thay i L cng sut mch t gi tr cc i. Khi cng sut ca mch l: A:100WB: 1002WC:200W D:400W Cu 51:Cho on mch c r,R,L,C mc ni tip. Trong r = R = 25, C = 10-3/53(F), L thay i c. t vo hai u mch mt ht xoay chiu n nhu = 1002sin100t (V). Thay i L cng hiu dng trong mch t cc i. Biu thc ca dng in i l: A: i = 22sin100t(A) B: i = 22sin(100t + /2)(A)C: i = 2sin(100t - /2) (A) D: i = 2sin(100t + /4 )(A) Cu 52:Mt on mch gm R = 100, mt cun thun cm c L thay i c v t in c C = 0,318.10-4 Fmc ni tip vo mch xoay chiu c uAB = 200cos(100t) (V). L phi c gi tr bao nhiu cng sut ln nht? PMax = ?A:L = 0,318(H), P = 200W B:L = 0,159(H), P = 240WC:L = 0,636(H), P = 150W D:Mt gi tr khcCu 53:Mt on mch gm din tr R=100 ni tip vi C0 = 10-4/(F) v cun dy c r = 100, L = 2,5/(H). Ngun c u = 1002sin(100t) (V). cng sut ca mch t gi tr cc i, ngi ta mc thm mt t C1 vi C0: A:C1 mc song song vi C0 v C1 = 10-3/15(F)B:C1 mc ni tipvi C0 v C1 = 10-3/15(F)C:C1 mc song song vi C0 v C1 = 4.10-6/(F)D:C1 mc ni tipvi C0 v C1 = 4.10-6/(F) Cu 54:Mch RLC ni tip: L = 159(mH); C = 15,9F, R thay i c. Ht t vo hai u on mch u = 1202cos100t (V). Khi R thay i th cng sut tiu th cc i ca on mch l: A:240WB:48W C:96W D: 192W Cu 55:Mch in xoay chiu RLC mc ni tip, vi R = 10O, cm khng ZL = 10O, dung khng ZC = 5O ng vi tn s f. Khi f thay i n f th trong mch c hin tng cng hng in. Hi t l no sau y l ng? A A: : 2f= fB. f = 0,5fC. f= 4fD. f= 2f Cu 56:Hai u on mch RLC, cun dy thun cm, c duy tr in p uAB = U0coset (V). Thay i R, khi in tr c gi tr R = 24 th cng sut t gi tr cc i 300W.Hi khi in trbng 18 th mch tiu th cng sut bng bao nhiu ? A: 288 WB. 168WC. 248 WD. 144 W Cu 57:oan mach AB gom hai oan AD vaDB ghep noi tiep. ien ap tc thi tren cac oan mach vadong ien qua chung lan lt cobieu thc: uAD = 1002cos(100tt + t/2)(V);uDB = 1006cos(100tt + 2t/3)(V); i =2cos(100tt + t/2)(A). Cong suat tieu thucua oan mach AB la: A: 100WB. 242WC. 186,6WD. 250W. Cu 58:Hieu ien thexoay chieu hai au mach n nh v c biu thc: u = U0coset (V). Khi C = C1 th cong suat mach laP = 200W vacng oong ien qua mach la: i =I0cos(et - t/4 ) (A). Khi C = C2 th cong suat mach cc ai. Tnh cong suat mach khi C = C2. A: 400WB: 4002W C: 800W D: 2002W. Gv: Nguyn Hng Khnh _ HKP PHNG PHP GII BI TP DNG IN XOAY CHIU LTHDi ng: 09166.01248 Email: Khanhcaphe@gmail.com Gio Dc Hng Phc - Ni Khi u c M! HP 28 Cu 59:Cho on mch xoay chiu AB gm in tr R v mt cun dy mc ni tip. in p t vo hai u on mch c tn s 50Hz v c gi tr hiu dng U khng i. in p hiu dng gia hai u ca R v gia hai u ca cun dy c cng gi tr v lch pha nhau gc t/3. h s cng sut bng 1 th ngi ta phi mc ni tip vi mch mt t c in dung 100F v khi cng sut tiu th trn mch l 100W. Hi khi cha mc thm t th cng sut tiu th trn mchbng bao nhiu ? A: 80WB. 86,6WC. 75WD. 70,7W. Cu 60:t vo 2 u mch in c 2 phn tC v R vi in tr R = ZC = 100O mt ngun in tng hp c biu thc u = [1002cos(100tt + t/4) + 100]V. Tnh cng sut ta nhit trn in tr: A: 50WB: 200WC: 25WD: 150W. Cu 61:Mt mch in xoay chiu gm 3 phn t R,L,C, cun dy thun cm. Mc mch in trn vo ngun in xoay chiu c gi tr hiu dng U khng i th thy hiu in th 2 u mi phn t l nh nhau v cng sut tiu th ca mch l P.Hi nu b t C ch gi li R,L th cng sut tiu th ca mch l P s bng bao nhiu theo P? A: P = PB: P = 2PC: P = 0,5PD: P = P/ 2 Cu 62:Mch in xoay chiu RLC ghp ni tip, t vo hai u mch mt hiu in th u = U0cost (V). iu chnh C = C1 th cng sut ca mch t gi tr cc i Pmax = 400W. iu chnh C = C2 th h s cng sut ca mch l 32. Cng sut ca mch khi l: A:200WB: 1003W C: 100WD:300W Cu 63:Mch in xoay chiu R L C c R thay i cmc vo hiu in th xoay chiuu 200cos100 tV = t . Bit khi R 50 = O vR 200 = O th cng sut mch in u bng nhau v bng P. Gi tr ca P l: A. 80WB. 400WC. 160WD. 100W Cu 64:C hai hp kn m trong mi hp cha 2 trong 3 phn t R L C mc ni tip. Khi ln lt mc vo hai u mi hp hiu in th xoay chiuu 200cos100 tV = tth cng dng in hiu dung v cng sut mch in tng ng u l I v P. em ni tip hai hp v duy tr hiu in th trn th cng dng in cng l I. Lc cng sut ca on mch l: A. 4PB. PC. 2PD. P/2 Cu 65:t vo hai u mt cun dy c t cm L = 0,4H mt hiu in th mt chiu U1 = 12 V th cng dng in qua cun dy l I1 = 0,4 A. Nu t vo hai u cun dy ny mt in p xoay chiu c gi tr hiu dng U2 = 120 V, tn s f = 50 Hz th cng sut tiu th cun dy bng A: 360 W.B: 480 W.C: 16,2 W.D: 172,8 W. Cu 66:Cho mch in xoay chiu RLC mc ni tip, c R l bin tr. t vo hai u on mch hiu in th xoay chiu c biu thc 120 2 cos(120 ) u t = V. Bit rng ng vi hai gi tr ca bin tr : R1=38 O, R2=22 O th cng sut tiu th P trn on mach nh nhau. Cng sut ca on mch khi nhn gi tr no sau y: A: 120 WB: 484 WC: 240 WD: 282 W Cu 67:Mch RLC mc ni tip, in p hiu dng hai u on mch c gi tr 120V, in tr R thay i c cn cc thng s khc ca mch c gi tr khng i. Khi thay i R th thy vi R = R1 = 80 hoc R = R2 = 45 th mch c cng cng sut P. Gi tr ca P l A: 96WB: 60WC: 115,2WD: 115W Cu 68:Mt cun dy c in tr thun O = 3 100 R v t cm L = 3/H mc ni tip vi mt on mch X c tng tr ZX ri mc vo in p c xoay chiu c gi tr hiu dng 120V, tn s 50Hz th thy dng in qua mch in c cng hiu dng bng 0,3A v chm pha 300 so vi in p gia hai u mch. Cng sut tiu th trn on mch X bng: A: 0W 4B: W 3 9C: W 3 18D: W 30 Gv: Nguyn Hng Khnh _ HKP PHNG PHP GII BI TP DNG IN XOAY CHIU LTHDi ng: 09166.01248 Email: Khanhcaphe@gmail.com Gio Dc Hng Phc - Ni Khi u c M! HP 29 CHNG IV: DNG IN XOAY CHIU BI 4: HIU IN TH V CC TR HIU IN TH I. PHNG PHP 1. T CM THAY I. Cho mch RLC c L thay iA.L thay i U R max

U R = I.R = U.RR2 + ( Z L - Z C)2

L thay i khng nh hng n t; U R maxkhi mu t gi tr nh nht. Z L = Z C( Hin tng cng hng) B.L thay i U C max

U C = I. Z C = U. Z CR2 + (Z L - Z C)2 Tng t nh trn: U C maxkhi mch c hin tng cng hng.C. Nu L thay i U L max U L = I. Z L = U. Z L Z= U. Z LR2 + ( Z L - Z C)2 ( Chia c t v mu cho Z L) = UR2 Z L2 + (Z L - Z C )2 Z L2 = UY U L max khi Y min

Y = R2 Z L2 + 1 - 2 Z CZ L+ Z C2 Z L2 =R2 + Z C2 Z L2 - 2 Z CZ L+ 1. (t x = 1Z L ) Y = ( R2 + Z C2 ) .x2 - 2. Z C.x + 1 Cch 1: Phng php o hmY = 2( R2 + Z C2 ).x - 2. Z C= 0 x = Z CR2 + Z C2

Y = 2.(R2 + Z C2 ) >0 Khix = Z CR2 + Z C2 th Y min

x = Z CR2 + Z C2 = 1Z L Z L= R2 + Z C2 Z C

Cch 2: Phng php th Y = ( R2 + Z C2 ) .x2 - 2. Z C.x + 1 V ( R2 + Z L2 ) > 0 th c dng nh hnh v Y minkhix = - b2a= Z CR2 + Z C2 = 1Z L Z L = R2 + Z C2 Z C

Y min= -A4a= R2 R2 + Z C2 U L max = UY

U LMAX = UZ C2 +R2 RU L max = U U C2 + U R2 U R

-A4a x y - b2a

Cch 3: Dng gin : p dng nh l sin ta c: U Lsin |= Usino U L = Usino. sin | (1) Ta li c: sin o = U RU RC= U RU R2 + U C2 (2) Thay (2) vo (1): U L = U U R2 + U C2 U R.sin | U L t gi tr ln nht khi sin | = 1.( tc | =t2 ) U U L U C U R U RC | o Gv: Nguyn Hng Khnh _ HKP PHNG PHP GII BI TP DNG IN XOAY CHIU LTHDi ng: 09166.01248 Email: Khanhcaphe@gmail.com Gio Dc Hng Phc - Ni Khi u c M! HP 30 U L max = U U R2 + U C2 U RHoc U L max= U R2 + Z C2 R

D.BI TON PH: bi: Mch RLC c L thay i, khi L = L 1v L = L 2 th thy U Lu nh nhau. Xcnh L hiu in thhai u mch t cc i.Hng dn:U Lmaxkhi 12

(( 1Z L 1 + 1Z L 2= 1Z L L = 2L 1.L 2L 1 + L 2 2: IN DUNG THAY I.A.C thay i U R max; U L max( Phn tch tng t nh trn) Z L = Z C eL = 1eC C = 1e2 L

B. C thay i U Cmax Z C =R2 +Z L2 Z L U CMAX = UZ L2 +R2 R

C. BI TON PH: bi: Mch RLC c C thay i. Khi C = C 1v C = C 2 th thy U Cu nh nhau. U C trong mch t cc i th in dung ca t phi l bao nhiu? Hng dn: U C maxkhi: 12

((1Z C 1 + 1Z C 2 = 1Z C C = C 1 + C 2 2

3: IN TR THAY I. A.R thay i U Rmax:U R = I .R = U.RR2 + (Z L - Z C)2 = U1 + (Z L - Z C)2 R2 t Y = 1 + (Z L - Z C)2 R2

U R = UY U R max khi Y min

Y minkhi (Z L - Z C)2 R2 = 0 R B. R thay i U Lmax:U L= I. Z L= U. Z LR2 + ( Z L - Z C)2 U L maxkhi R = 0. B.R thay i U C max:U C = I.Z C= U. Z CR2 + (Z L - Z C)2 U C max khi R = 0 4: THAY I TN S GC: A.e thay i U Rmax: U R = I.R = U.RR2 + ( Z L - Z C)2 U R maxkhi Z L = Z C ( cng hng)e = 1LCf = 12tLC

B. e thay i U Cmax : U C= I. Z C = U eCR2 + ( eL + 1eC )2 = UCe2 R + e4 .L2 - 2.e2 LC + 1C2

= UC.Y

ViY = e4 .L2 + e2 ( R2 - 2LC )+ 1C2 Vy U C t gi tr cc i khi Y min : t x = e2 . Y c dng:Y = L2 . x2 + ( R2 - 2LC ). x+ 1C2 ( L2 > 0) Y t gi tr nh nht kh:x = - b2a= 2LC - R2 2L2 = 1LC- R2 2L2 = e2 . Gv: Nguyn Hng Khnh _ HKP PHNG PHP GII BI TP DNG IN XOAY CHIU LTHDi ng: 09166.01248 Email: Khanhcaphe@gmail.com Gio Dc Hng Phc - Ni Khi u c M! HP 31 Y min ( TcU C max) khi: e =1LC - R2 2L2 Hoc f = 12t 1LC - R2 2L2

***Bi ton ph: Mch RLC c tn s gc thay i c, Khi e = e 1 v khi e = e 2 th U C trong mch l nh nhau. Xc nh gitr ca e U C trong mch t gi tr ln nht: e2 = 12[ ] e 12 + e 22

C. ethay i U L max: ( Phn tch tng t) e = 1LC - C2 R2 2 f =12t 1LC - C2 R2 2 ***Bi ton ph: Mch RLC c tn s gc thay i c, Khi e = e 1 v khi e = e 2 th U Ltrong mch l nh nhau. Xc nh gi tr ca e U Ltrong mch t gi tr ln nht:1e2 = 12

((1e 12 + 1e 22 6. MCH RLC C C THAY I U R C MAX

U RC = I. Z RC= U. Z RCZ= UR2 + Z C2 R2 + (Z L - Z C)2 = U.Y U R C t gi tr cc i khi Y t gi tr cc i( Y max ) t U = R2 + Z C2 V = R2 + ( Z L - Z C)2 U Z C = 2. Z C V Z C = - 2( Z L - Z C) Y = U.V - V.UV2 = 2.Z C [ ] R2 + ( Z L - Z C)2 + 2( Z L - Z C) ( R2 + Z C2 )[ ] R2 + ( Z L - Z C)2 2 = 0 2. Z C.R2 + 2Z C. Z L2 - 4Z L. Z C2 + 2. Z C3 + 2Z L.R2 + 2Z L. Z C2 - 2Z C.R2 - 2. Z C3 = 0 - 2. Z L. Z C2 + 2. Z C. Z L2 + 2. Z L.R2 = 02Z L ( Z C2 - Z L. Z C- R2 ) = 0 Z C2 - Z L. Z C- R2 = 0. Gii phng trnh bc 2 theo Z C ta c: Z C = Z L +Z L2 + 4R2 2

7. MCH RLC C L THAY I U RL MAX: Tng t nh phn trn ( C thay i U Cmax ). Z L2 - Z C. Z L - R2 = 0 Z L = Z C +Z C2 + 4R2 2

II. BI TP THC HNH. Cu 1: on mch RLC c L thay i c mc vo mng in xoay chiu c hiu in th khng i. Vit cng thc xc nh Z L hiu in th hai u t in t cc i? A: Z L = 2Z C B: Z L = RC: Z L = R2 + Z C2 Z C D: Z L = Z C

Cu 2: on mch RLC c L thay i c mc vo mng in xoay chiu c hiu in th khng i. Vit cng thc xc nh Z L hiu in th hai u cun cm t cc i? A: Z L = 2Z C B: Z L = RC: Z L = R2 + Z C2 Z C D: Z L = Z C

Cu 3: on mch RLC c C thay i c mc vo mng in xoay chiu c hiu in th khng i. Vit cng thc xc nh Z C hiu in th hai u cun cm t cc i? A. Z L = 2Z C B: Z C = R2 + Z L2 Z L C: Z C = 2Z LD: Z L = Z C

Cu 4: on mch RLC c R thay i c mc vo mng in xoay chiu c hiu in th khng i. Xc nh R hiu in th hai u cun cm t cc i? A: R tin v B: R tin v 0 C: R = | | Z L - Z CD: R = Z L - Z C Cu 5: on mch RLC c R thay i c mc vo mng in xoay chiu c hiu in th khng i. Xc nh R hiu in th hai u in tr t gi tr cc i? A: R tin v B: R tin v 0 C: R = | | Z L - Z CD: R = Z L - Z C

Gv: Nguyn Hng Khnh _ HKP PHNG PHP GII BI TP DNG IN XOAY CHIU LTHDi ng: 09166.01248 Email: Khanhcaphe@gmail.com Gio Dc Hng Phc - Ni Khi u c M! HP 32 Cu 6: on mch RLC c f thay i c mc vo mng in xoay chiu c hiu in th khng i. Xc nh f hiu in th hai u in tr t gi tr cc i? A: f = 1LC B: f = 12LC C: f = 12t .1LC D: f =2tLC

Cu 7: Mch RLC c R = 20 , L = 0,4/tHv t in C c th thay i. Mc mch in trn vo mngin 220 V - 50 Hz.-Tm gi tr ca C U R t gi tr cc i? A: C = 10-4 4t F. B: C = 4.10-4 t FC: C =2,5.10-4 t FD: 10-3 6t F -Tm gi tr cng sut khi ? A: 242WB: 2420WC: 2020WD: 2200W Cu 8: Mch RLC c R = 30 , L = 0,3/tHv t in C thay i. Mc mch in trn vo mng in 220 V - 50 Hz. -Tm gi tr ca C U L t gi tri cc i? A: C = 30 FB: Z C = 10-3 t C: C = 10-3 t FD: Khng p n-Tm gi tr cng sut khi ? A: 1600WB: 300WC: 1631WD: 1613W Cu 9: Mch RLC c R = 30 , L = 0,3/tHv t in C thay i. Mc mch in trn vo mngin 220 V - 50 Hz. Tm gi tr ca C U C t gi tri cc i? A: C = 10-4 6t FB: C =10-3 6t FC: C = 6.10-4 t FD: C = 60 Cu 10: Mch in RLC c L thay i c, trong R = 30 , C = 10-4 /2t F. Mch in trnc gn vo mng in 220 V - 50 Hz.-Tm gi tr ca Z L U C t cc i?A: Z L = 100 B: Z L = 50 C: Z L = 20 D: Z L = 200 -Tnh gi tr U Cmax khi ? A: 40 V B: 49,4VC: 1466,7 VD: 2000V Cu 11: Mch RLC c L thay i c R = 40 , C = 10-3 /4t F, c gn vo mng in 200 V - 40 Hz. Xc nh L gi tr ca U L max ? A. L = 8t HB: L =0,8t HC: L =t0,8 HD: L = 80 Cu 12:Mch RLC c C thay i khi C = 10-3 / 4t F v khi C = 10-3 /6t F th hiu in th hai u t l nh nhau. Hi C bng bao nhiu th hiu in th hai u t in t cc i? A: C = 5.10-3 24t FB: C = 10-4 5t FC: 10-3 5t FD: C = 5.10-3 t F Cu 13:Mch RLC c L thay i, khi L = 0,318 H v khi L = 0,4 H th U L bng nhau, hi L bng bao nhiu th U L t gi tr cc i? A: 0,3 HB: 0,354 HC: 0,53HD: 0,65H Cu 14: Mch RLC mc theo th t c L thay i,R = 50 , C = 10-4 /tF. Mc mch in trn vo mng in 220 V - 50 Hz. Tnh gi tr U RLmax ? A: 400 VB. 492 VC: 500 VC: 515V Cu 15:Mch RLC mc ni tip c C thay i. Trong R = 50 , L = 1/tH c mc vo mng in 100V - 50 Hz. Khi Z C cn iu chnh n gi tr no U C t gi tr cc i? A: Z C = 100 B: Z C = 130 C: Z C = 150 D: Z C = 125 Cu 16: Mch RLC mc ni tip, c R v C c th iu chnh c. Trong L = 1/ 2tH. c mc vo mng in 150 V - 50 Hz. Ta phi iu chnh Z C n gi tr no khi iu chnh R th gi tr ca U R khng thay i? A: Z C = 200 B: 50 C: 100 D: 150 Cu 17: Mch RLCmc ni tip, c R v L c th iu chnh c, C = 10-4 2t F. Mch in trn c mc vo mng in 150V - 50 Hz. Ta phi iu chnh Z L n gi tr no khi iu chnh R th gi tr ca U R khng thay i? A: 200 B: 50 C: 100 D: 150 Cu 18: Mch RLC c L thay i trong R = 100 , C = 10-4 /t F, c gn vo mng in 200 V - 50 Hz, iu chnh L U L t gi tr cc i.Tnh cng sut ca mch in trong trng hp trn? A: 100WB: 200WC: 600 WD: 1200W Cu 19: Mch RLC c R - L mc lin tip nhau, c R = 40 , C = 10-3 / 6tF, mc vomng in 150 V - 50 Hz.-Tm gi tr ca Z L U RLmax? A: 76 B: 86 C: 66 D: 80 - V U RLmax khi ny c gi tr l bao nhiu? A: 300 VB: 120 VC: 102 VD: 210 V Cu 20: Mch RLC mc ni tip C c th thay i c, trong R = 100 , L =3 /t H. c mc vo mng in u = 200cos( 100tt) V.-Phi iu chnh t in C n gi tr no h s cng sut trong mch t gi tr cc i? Gv: Nguyn Hng Khnh _ HKP PHNG PHP GII BI TP DNG IN XOAY CHIU LTHDi ng: 09166.01248 Email: Khanhcaphe@gmail.com Gio Dc Hng Phc - Ni Khi u c M! HP 33 A: C = 100 B: C = 1003 C: C = 10-4 3t FD: C = 10-3 3t F - iu chnh C n gi tr U C max. Hy tnh gi tr U Cmax? A: 200VB: 300VC: 2002 VD: 3002 V Cu 21:Mch RLC c L thay i c, c mc vo mng in u = 200 cos( 100tt + t/3) A. Trong mach c R = 503 , C = 10-3 /5tH.-Phi iu chnh L n gi tr no U L max? A:L = 0,2t HB. L = 12t HC: L = 2t HD: L = 10,2t H - Tm U L max? A: 200 6|3 VB: 220VC: 20002 VD: 2002 V Cu 22:Cho mch RLC c C thay i c, trong R = 40 , cun cm thun c L = 0,3/tH v t in C thay i c. Hai u on mch mc vo ngun in xoay chiu u = 120 V, tn s f = 50 Hz. TmZ C U L max? A: Z C = 20 B: Z c =2 C: Z C = 200 D: Z C = 30 Cu 23:Mch RLC mc ni tip, trong R = 60 , cun cm thun c t cm L thay i v t c C = 10-3 /8tF. Hai u mch in mc vo ngun in xoay chiu c U khng iv bng 100 V v f = 50 Hz. iu chnh L hiu in th hai u cun dy ch cc i, tm gi tr L khi ? A: L =t1,25 HB:L = 12,5t HC: L =1,25t HD: L = 125t H Cu 24: MchRLCtrongR=30,C=10-3 /4tFvcuncmthuncLthayi.Haiuonmch mc vo ngun in xoay chiu u = 1502 cos 100tt V. iu chnh L hiu in th hai u cun dy t cc i. Tmtr hiu in th cc i ? A: 25VB: 150VC: 200VD: 250V Cu 25: Mch RLC c C thay i, gn mch in vo mng in c u = 1502 cos 100tt V. Khi C =10-3 /3t F th U L max,vgi tr cc i ch 120V. Tm gi tr in tr ca mch in? A: 30 B: 40 C: 50 D: 37,5 Cu 26:Cho on mch xoay chiu gm in tr thun R, cun cm thun c t cm L thay i v t in C = 10-3 /3tF mc ni tip, mc vo mng in u = 1002 cos( 100tt) V. iu chnh L hiu in th hai u cun dy t cc i v gi tr cc i l 125 V. Tm ln L = ? A: L = 1t HB: L =0,83t HC: L =0,38t HD: L =0,5t H Cu 27:Cho on mch gm cun dy L,r c r = 50 , L c th thay i c, mc ni tip vi t in C khng i. Hai u on mch mc vi ngun xoay chiu c u = 169,7cos100tt V. iu chnh L v lc L = 0,318H th U C t gi tr cc i, tm gi tr U C khi ? A: 120 VB: 200VC: 420VD: 240V Cu 28:Mch in gm cun dy c r = 40 , L = 0,4/tH, t in c in dung C thay i c. Mch in trn c ni vo ngun in u = 1202 cos( 100tt) V. Thay i C Vn k ch cc i( Vn k mc vo hai u C), Tm gi tr cc i ca vn k? A: 120VB: 1202 C: 1203 VD: 200V Cu 29: Mch RLC trong mch c R = 50 , L = 0,4/tH; C = 10-3 /4t. Mach in trn c gn vo mng in xoay chiu cU = 200 V v tn s c th thay i.-Tm gi tr ca tn s f hiu in th trn hai u in tr t cc i?A: f = 60HzB: 35HzC: 40HzD: 50Hz -Tm gi tr cng sut khi ? A: 400WB: 1200WC: 1000WD: 800W Cu 30:Mch RLC trong mch c R = 60 , L = 0,5/tH; C = 10-3 /5t. Mach in trn c gn vo mng cU = 200 V v tn s gc c th thay i.-Tm gi tr ca e hiu in th trn hai u in tr t cc i?A. 80t Rad/sB: 70tRad/sC: 100t Rad/sD: 120t Rad/s -V tm h s cng sut khi ? A: cos = 0,5B: cos = 32 B: cos = 22 D: cos = 1.Cu 31:Mt on mch gm in tr R = 100 , cun dy c r = 80 , L = 0,3 H v t C bin thin. Mc vn k vo hai u cun dy. Hai u on mch mc vo mch in u = 1202 cos( 120tt) V. iu chnh C V k ch cc i, S ch cc i l: A: 50 VB: 114,5VC: 86,4VD: 92,3 V Cu 32:Mch RLC ni tip, c cun dy thun cm, tn s dng in c th thay i c. Phi thay i f n gi tr no hiu in th hai u t in t gi tr cc i? Gv: Nguyn Hng Khnh _ HKP PHNG PHP GII BI TP DNG IN XOAY CHIU LTHDi ng: 09166.01248 Email: Khanhcaphe@gmail.com Gio Dc Hng Phc - Ni Khi u c M! HP 34 A:f = 12t

1LC - R2 2L2 B: f = 12t

1LC + R2 .C2 2 C: f = 12t

1LC + R2 .C2 2 D:f = 12t

1LC - 2L2 R2 Cu 33:Mch RLC ni tip, c cun dy thun cm, tn s dng in c th thay i c. Phi thay i f n gi tr no hiu in th hai u cun dy cc i? A: f = 12t

1LC + R2 .C2 2B:f = 12t

1LC - R2 2L2 C: f = 12t 1LC - C2 R2 2 D:f = 12t

1LC - 2L2 R2

Cu 34:Cho on mch xoay chiu RLC, trong cun dy c r = 40 , L thay i c, mc ni tip vi t C. Hai u on mch mc vo ngun xoay chiu c U AB khng i v e = 100t rad/s. Khi L = 0,6/t H th U AM t cc i( U AM l hiu in th hai u cun dy). in dung C ca t l: A: 1/t 10-4 FB: 1/2t. 10-4 FC: 3/t. 10-4 FD: 3/2t. 10-4 FCu 35:Mch in xoay chiu RLC ni tip cR ZC3 = , in p xoay chiu gia hai u on mch c gi tr hiu dng v tn s khng i. Thay i t cm ca cun dy (thun cm) in p hiu dng gia hai u cun dy ln nht. H s cng sut ca mch c gi tr bng A:2 / 3 B: 1/2C:2 / 2 D. 3/4 Cu 36:Mt cun dy mc ni tip vi t in c in dung thay i c ri mc vo ngun in xoay chiu c biu thc 0os( ) u U c t = (V) Thay i in dung ca t in in p hiu dng hai u t t cc i th khi in p hiu dng gia hai bn t l 2Uo . in p hiu dng gia hai u cun dy lc ny l A: 3,5U0B: 3U0.C: 07U2D: 02U. Cu 37:Mt cun dyghp ni tip vi mt t in. t vo hai u mch mt hiu in th xoay chiu c gi tr hiu dng khng i U = 100V. iu chnh C hiu in th hiu dng hai u t t c gi tr cc i UCmax = 200V. H s cng sut ca mch khi l: A:1B:3 /2C: 1/2D:2 /2 Cu 38:Mt ng dy c in tr thun R, cm khng ZL mc ni tip vi mt t in c dung khng ZC v mc vo mch in xoay chiu. Bit hiu in th hai u cun dy, hai u t v hai u on mch t l: 1: 2 : 3. H thc lin h no sau ph hp vi mch in trn? A. 2( )L C LR Z Z Z = B. 2( )L L CR Z Z Z = C. 2L CR Z Z = D. L CZ Z =Cu 39:t vo hai u on mch RLC mt in pu 160 2.cos100 t(V) = t , cun dy c (r = 0), L thay i c. iu chnh L hiu in th hai u cun dy t gi tr cc i v c gi tr ULmax = 200V th URC bng: A: 106VB: 120VC: 160VD: 100V Cu 40:t in p xoay chiu c tr hiu dng100 3U V =vo hai u on mch RLC c L thay i. Khi in p hiu dng ULMax th UC=200V. Gi tr ULMax l A: 100 VB: 150 VC: 300 VD: p n khc.Cu 41:Mt mch in gm in tr thun R, cun dy thun cm v mt t in c in dung thay i c mc ni tip. t vo hai u on mch trn mt in p xoay chiu c biu thc2 cos ( ) = u U t V . Khi thay i in dung ca t cho in p hiu dng gia hai bn t t cc i v bng 3U. Ta c quan h gia ZL v R l A: ZL = 3RB: ZL =3 RC: ZL =2 2 RD: ZL = 2R Cu 42:Mch RLC ni tip c hai u mch l A v B, C l mt im nm gi R v L, cun dy thun cm c L thay i c . Khi L thay i UL t cc i kt lun no sau y l sai : A:2 2maxAB CLCU R ZUZ+=C: U2 Lmax= U2 AB+ U2 RC\ B:2 2CLCR ZZZ+= D: uAB vung pha vi uRC

Cu 43:Mch xoay chiu RLC ni tip .Trng hp no sau y in p hai u mch cng pha vi in p hai u in tr R:A. Thay i C URmax B. Thay i L ULmax C. Thay i f UCmax D. Thay iR UCmax

Cu 44:Mt mch in gm in tr thun R, cun dy thun cm v mt t in c in dung thay i c mc ni tip. t vo hai u on mch trn mt in p xoay chiu c biu thc2 cos ( ) = u U t V . Khi thay i in dung ca t cho in p hiu dng gia hai bn t t cc i v bng 2U th quan h gia ZL v R l Gv: Nguyn Hng Khnh _ HKP PHNG PHP GII BI TP DNG IN XOAY CHIU LTHDi ng: 09166.01248 Email: Khanhcaphe@gmail.com Gio Dc Hng Phc - Ni Khi u c M! HP 35 A: ZL = 2RB: ZL =2 2 RC: ZL = 3RD: ZL =3 R Cu 45:Cho on mch R, L, C ni tip vi L c th thay i cTrong R v C xc nh. Mch in c t diin p u = U 2 sint. Vi U khng i v cho trc Khi in p hiu dng gia hai u cun cm cc i. Gi tr ca L l A: L = R2 + 2 21CB: L = 2CR2 + 21CC: L = CR2 + 212CD: L = CR2 + 1Ce2

Cu 46:Mt on mch R-L-C mc ni tip. t vo hai u on mch mt in p xoay chiu c gi tr hiu dng 200V, tn s thay i c. Ti tn s 50Hz in p hai u cun dy thun cm cc i bng 250V, ti tn s 60Hz in p hai bn t cc i. cng sut trong mch cc i ta cn iu chnh tn s n gi tr A: 10 3 HzB: 10 30 HzC: 3000HzD: 10Hz Cu 47:Mch in xoay chiu RLC ni tip trong cun dy thun cm, t in c in dung thay i c. Mc vo hai u mch mt hiu in th) ( 2 t Cos U u = v iu chnh in dung ca t sao cho s ch vn k mc vo hai u t c gi tr ln nht lU 2 . Gi tr tn s gc ca mch khi l:A: LR3B:LR 3 C: LR D: LR32 Cu 48:Cho mch in khng phn nhnh AMB gm in tr thun R thay i c gi tr, cun dy c t cm L, in tr thun r v mt t in c in dung C mc ni tip theo ng th t trn, M nm gia cun dy v t in. in p hai u mch c gi tr hiu dng n nh c dng u = U 2 cos(200 t)V. Thay i gi tr ca R ngi ta thy in p hiu dng trn AM khng i. Tm nhn xt sai A: H s cng sut ca mch l 2 2( )CR rR r Z++ +B: Mch cng hng vi tn s 100 2 Hz. C: UAM = U.D: Mch c tnh dung khng Cu 49:t in p u=U2cos et vo hai u on mch RLC ni tip. Trong U, e, R v C khng i. iu chnh L in p hiu dng trn L t cc i. Chn biu thc sai A: 2 2 2 2R L CU U U U = + + B: 2 20L C LU U U U =C: 2 2L C CZ Z R Z = + D: 2 2CLU R ZUR+= Cu 50:Mt mch in xoay chiu gm cc linh kin l tng R, L, C mc ni tip. Tn s gc ring ca mch l e0, in tr R c th thay i. Hi cn phi t vo mch mt in p xoay chiu c gi tr hiu dng khng i, c tn s gc e bng bao nhiu in p hiu dng URL khng ph thuc vo R? A: e = 02eB: e = e0.C: e = e0 2D: e = 2e0 Gv: Nguyn Hng Khnh _ HKP PHNG PHP GII BI TP DNG IN XOAY CHIU LTHDi ng: 09166.01248 Email: Khanhcaphe@gmail.com Gio Dc Hng Phc - Ni Khi u c M! HP 36 CHNG IV: DNG IN XOAY CHIU BI 5: PHNG PHP GIN VEC T - BI TON HP EN I.BI TON HP EN Cha kha 1: lch pha u v i. 1.Hp en c 1 phn t: -Nu =t2 rad l L -Nu = 0 rad l R -Nu = -t2 l C X 2.Hp en cha hai phn t: -Nut2> > 0 l RL - Nu-t2< < 0 l RC - Nu = t2 l LC Cha kha 2: Cn c vo hiu in th: ( Cho s nh hnh v, gi s trong X v Y ch cha mt phn t) - NuU = |U X- U Y | l L v C - Nu U =U X2 + U Y2 l

R v C R v L - Nu U = U X + U Y X v Y cha cng mt loi phn t( cng R, cng L hoc cng C)

XY U xU y U II. PHNG PHP GIN VECTO 1.C S L THUYT HNH HC a.Cc cng thc lung gic c bn trong tam gic vung Sin = iHuyn= ca Cos = KHuyn= ba Tan = iK= cb Cotan = Ki= bc A B C b a c b.Cc h thc trong tam gic vung nh l 1 :(Pitago) BC2 = AB2 + AC2 nh l 2 : AB2 = BC.BH AC2 = BC. CH

nh l 3 :AH2 = BH.CH nh l 4 : AB.AC = BC.AH nh l 5 : 1/AH2 = 1/AB2 + 1/AC2 Gv: Nguyn Hng Khnh _ HKP PHNG PHP GII BI TP DNG IN XOAY CHIU LTHDi ng: 09166.01248 Email: Khanhcaphe@gmail.com Gio Dc Hng Phc - Ni Khi u c M! HP 37 A B C b a c H c.nh l cos - sin nh l cos: a2 = b2 + c2 - 2b.c.cos nh l sin:asin A= bsin B=csin C

A BC a bc d.Cc kin thc khc: -Tng ba gc trong tam gic l 180o

- Hai gc b nhau tng bng 180o

- Hai gc ph nhau tng bng 90o

-Nm kin thc v tam gic ng dng, gc i nh, sole, ng v .. 2.C S KIN THC VT L: -Z =R2 + ( Z L - Z C)2 ; U =U2 R + (U L - U C)2

-Cos = RZ= U RU ; tan = Z L - Z C R

- nh lut :I = U RR= U LZ L = U CZ C = UZ

- Cng thc tnh cng sut: P = U.I. cos = I2 .R - Cc kin thc v cc linh kin R,L,C. Mch ch c L:+ u nhanh pha hn i gc 2

+ Gin vc t iu L

Mch ch c C: + u chm pha hn i gc 2

+ Gin vc t iu L

Mch ch c R: + u v i cng phaGv: Nguyn Hng Khnh _ HKP PHNG PHP GII BI TP DNG IN XOAY CHIU LTHDi ng: 09166.01248 Email: Khanhcaphe@gmail.com Gio Dc Hng Phc - Ni Khi u c M! HP 38 + Gin vc t u i Ch : Hai ng thng vunggc: K 1. K 2 = -1. tan 1 .tan 2= -1. Nu hai gc ( 1 > 0; 2 >0) 1 + 2 = 90o tan 1. tan 2= 1 Hoc: 1 < 0; 2 < 0 1 + 2 = - 90o tan 1. tan 2= 1 tan ( 1+ tan 2) = tan 1 + tan 21 - tan 1. tan 2

Gv: Nguyn Hng Khnh _ HKP PHNG PHP GII BI TP DNG IN XOAY CHIU LTHDi ng: 09166.01248 Email: Khanhcaphe@gmail.com Gio Dc Hng Phc - Ni Khi u c M! HP 39 3.CC PHNG PHP V GIN 3.1V ni tip: V d 1 : Mch RLC mc ni tip, trong : 2R = 2Z L = Z C; xc nh h s gc ca mch trn? Gii: Ta c: Z L = R Z C = 2R

V d 2: Mch RL ni tip c mc vo mng in xoay chiu c phng trnh hiu in th u = 2002cos( 100tt +t3 ) V, th thy trong mch c dng in i = 22 cos( 100tt) A. Hy xc nh gi tr ca R v L? Gii: Z = UI= 2002= 100 =t3rad R = Z.cos = 100 cost3= 100 12= 50 Z L = Z. sin = R.tan = 50. tant3= 503 L = Z Le=503100t=0,53tH

V d 3: Mch RLC ni tip ( trong cun dy thun cm Z L = 503 ). c mc vo mng in xoaychiu c phng trnh hiu in th u= 1002cos( 100tt -t6 ) V, th thy dng in trong mch cm t bng phng trnh i =2 cos( 100 tt +t6 ) A. Hy xc nh gi tr ca R v C. Gii: Ta c: Z = UI= 1001= 100 = -t3 ( Z C > Z L ) Ta c gin sau: R = Z.cos = 100. cost3= 50 (Z C - Z L) = R.tant3= 503 Z C = Z L + 503= 503 + 503= 1003

R Z C - Z L Z

t3

R Z L

Z ZZ L

Z C R Z C- Z L Gv: Nguyn Hng Khnh _ HKP PHNG PHP GII BI TP DNG IN XOAY CHIU LTHDi ng: 09166.01248 Email: Khanhcaphe@gmail.com Gio Dc Hng Phc - Ni Khi u c M! HP 40 V d 4: Mch RlC mc ni tip, C c th iu chnh c, c mc vo mng in xoay chiu c hiuin th U, Diu chnh t C u U C maxXc nh gi tr U C max.Gii: Theo nh l sin ta c: U Csin|= Usino U C = Usino . sin | Trong : sin o = U RU R L= U RU R2 + U L2 U C = U.U R2 + U L2

U R .sin | U C maxkhi sin | = 1 U C max=U.U R2 + U L2

U R V d 5: Mch RlC mc ni tip, C c th iu chnh c, c mc vo mng in xoay chiu c hiuin th U, Khi iu chnh C U C max th thy U C max= 2U. Hy tnh gi tr ca Z L theo R. Gii:

Ta c: U C = 2U sin o = UU C = U2U= 12 o =t6

tan o = U RU L= RZ L = 13 Z L =3 R V d 5: Mch gm cun dy c in tr thun ng k mc ni tip vi t C, C c th iu chnh c, hai u mch c mc vo mng in xoay chiu c hiuin th U = 80 V, iu chnh C U C max th thy U C max= 100 V. Xc nh hiu in th hai u cun dy? Gii:

Theo nh l Pitago ta c: Ucd =U C max2 - U2 =1002 - 802 = 60 V Cu 6 : Hai cun dy (R1, L1) v (R2, L2) mc ni tip ri mc vo ngun xoay chiu ht U. Gi U1 v U2 l ht 2 u mi cun. iu kin U = U1 + U2 l: A.L1/R1 = L2/R2 B.L1/R2 = L2/R1 C.L1.L2 = R1R2 D.L1 + L2 = R1 + R2

L 1 ; R 1 L 2 ; R 2

UU 1U 2 U = 80V U = 100VU L o| U R U cd U U = 2UU L o| U R U R L U U C

U L o| U R U R L Gv: Nguyn Hng Khnh _ HKP PHNG PHP GII BI TP DNG IN XOAY CHIU LTHDi ng: 09166.01248 Email: Khanhcaphe@gmail.com Gio Dc Hng Phc - Ni Khi u c M! HP 41

U = U 1 + U 2 khi hiu in th hai u cun dy cng pha tan 1 = tan 2

Z L 1R 1= Z L 2R 2eL 1R 1=eL 2R L 1R 1 = L 2R 2

Chn p n A Cu 1: Mch in AB gm cun dy c in tr trong r v t cm L, mc ni tip vi t in C. Gi U AM l hiu in th hai u cun dy v c gi tr U AM = 40 V, U MB = 60V hiu in th u AM v dng in i lch pha gc 30o . Hiu in th hiu dng U AB l: A. 122,3VB. 87,6V C. 52,9VD. 43,8V Gii: Theo nh l cos ta c: U AB2 = U AM2 +U MB2 - 2.U AM.U MB cos AMB = 402 + 602 - 2.40.60. cos 60o = 2800 U AB= 52,9V Chn p n C Cu 2: Mt onmch in xoaychiu cdngnhhnhv.Bithiu in th uAE v uEB lch pha nhau 900.Tm mi lin h gia R,r,L,.C A B C r R,LE A. R = C.r.L B.r =C. R..L C. L = C.R.rD.C = L.R.r Gii: Gi 1 l gc lch gia hiu in th on AE v cng dng in trong mch 2 l gc lch gia hiu in th on EBv cng dng in trong mch V u AE vung pha u EB

tan 1. tan 2 = - 1. - Z Cr . Z LR= -1 1.eLeC.r.R= 1 L = C.r.R Chn p n C Cu 3: Cho mt mch in gm mt t in c in dung C mc ni tip vi bin tr R. Mc vo hai u mch in mt hiu in th xoay chiu c tn s f. Khi R=R1 th cng dng in lch pha so vi hiu in th gia hai u on mch mt gc 1. Khi R=R2 th cng dng in lch pha so vi hiu in th gia hai u on mch mt gc 2. Bit tng ca 1 v 2 l 90o. Biu thc no sau y l ng?A. 2 12 R RCf=. B. CR Rf 22 1=. C. 2 12R R Cf=. D. 2 121R R Cf=.Gii: V 1+ 2= 90o

tan 1.tan 2= 1L ; RUABMA M B 30o

60o

40V 60VU 1 U 2 R 1 R 2

Z L 2

Z L 1 1

2

UGv: Nguyn Hng Khnh _ HKP PHNG PHP GII BI TP DNG IN XOAY CHIU LTHDi ng: 09166.01248 Email: Khanhcaphe@gmail.com Gio Dc Hng Phc - Ni Khi u c M! HP 42 ( - Z CR 1 ). ( - Z CR 2 ) = 11eC.R 1. 1eCR 2= 1 e2 = 1 C2 .R 1.R 2

f = 12tCR 1. R 2

3.2Phng php v chung gc V d 1 : Mch RLC mc ni tip, trong : 2R = 2Z L = Z C; xc nh h s gc ca mch trn? Gii: Ta c: Z L = R Z C = 2R

tan = Z L - Z C R= R - 2R R= - 1 = -t4

cos = cos( - t4) = 22

3.3Phng php v hn hp ( kt hp chung gc v ni tip) Cu 4: Chomch innhhnhv 050 3 R= O,50L CZ Z = = OAMU v MBU lch pha 750. in tr R c gi tr l A.25 3OB. 50OC. 25OD. 50 3O Gii:Ta c: u AM lch phalch pha u MBgct2

u MB lch pha so vi i gct6

u AM lch pha vi i gct4

tan AM= Z CR= 1 R = Z C = 50 O p nB III. BI TP THC HNH Cu 1: onmchAB chgmmtphntcha xc nh(c thl R,L,hocC).Trong ta xc nh c biu thci = 4cos100tt A v biu thcu = 40 cos( 100tt + t/2) V. Hy xc nh phn t trn? V tnh gi tr ca n khi ? A: R = 10 B: C = 10-3 /tFC: L = 0,1/tHD: C = 10-4 /tFCu 2: onmchAB chgmmtphntcha xc nh(c thl R,L,hocC).Trong ta xc nh c biu thci = 4cos100tt A v biu thc u = 40 cos( 100tt - t/2) V. Hy xc nh phn t trn? V tnh gi tr ca n khi ? Z L = 50Zc = 50Ro = 503 MB AM 30o

45o

ZZ L

Z C R Z C- Z L B L, R0 RC M A Gv: Nguyn Hng Khnh _ HKP PHNG PHP GII BI TP DNG IN XOAY CHIU LTHDi ng: 09166.01248 Email: Khanhcaphe@gmail.com Gio Dc Hng Phc - Ni Khi u c M! HP 43 A: R = 10 B: C = 10-3 /tFC: L = 0,1/tHD: C = 10-4 /tF Cu 3: onmchAB chgmmtphntcha xc nh(c thl R,L,hocC).Trong ta xc nh c biu thci = 4cos100tt A v biu thcu = 40 cos( 100tt )V. Hy xc nh phn t trn? V tnh gi tr ca n khi ? Tnh cng sut ca mch in? A: R = 10 B: C = 10-3 /tFC: L = 0,1/tHD: C = 10-4 /tF Cu 4: onmch AB cha hai phn t trong ba phn t( R,L,C) nhng cha c xc nh. Bit rng biu thc dng in trong mch l i = 4cos( 100tt + t/3) A. V biu thc cng dng in trong mch l u = 200cos( 100tt + t/6). Hy xc nh hai phn t trn? Tnh cng sut trong mch? A: R v L; P = 4003 WB. R v C; P = 400WC: C v L; P = 4003 WD: R v C ; P = 2003 W Cu 5: onmchAB chahai phnt trong ba phnt( R,L,C) nhngcha c xc nh. Bit rng biu thcdng in trong mch l i = 4cos( 100tt - t/3) A. V biu thc cng dng in trong mch l u = 200cos( 100tt + t/6). Hy xc nh hai phn t trn? V tnh cng sut trong mch? A: R v C; P = 0WB: R v L; P = 4003 WC: L v C; P = 0WD:L v C; P = 400 3 W Cu 6: onmchAB chahai phnt trong ba phnt( R,L,C) nhngcha c xc nh. Bit rng biu thcdng in trong mch l i = 4cos( 100tt - t/6) A. V biu thc cng dng in trong mch l u = 200cos( 100tt + t/6). Hy xc nh hai phn t trn v tnh gi tr ca chng? A: R = 253 ; Z L = 25 B: R = 25 ; Z L = 253 C: R = 50 ; Z L = 503 D: R = 503 ; Z L = 50 Cu 7: on mch AB gm hai phn t X,Y trong U X = 50 V, U Y = 20 V v gi tr hiu in th U AB = 30 V. vy phn t X,Y l g? A: R v CB: R v LC: L v CD: Khng c p nCu 8: on mch AB gm hai phn t X,Y trong U X = 40 V, U Y = 30 V v gi tr hiu in th U AB = 50 V v u nhanh pha hn i. Vy phn t X,Y l g? A: R v LB:R v CC: L v CD: A hoc B Cu 9: on mch AB gm hai phn t X,Y trong U X = a V, U Y = a3 V v gi tr hiu in th U AB = 2a V v u chm pha hn i. Vy phn t X,Y l g? A: R v LB:R v CC: L v CD: A hoc B Cu 10:Cho mch in gm hai phn t x,y mc ni tip, trong : x,y c th l R,L hoc C. Cho bit hiuin th gia hai u on mch u AB = 2002 cos100tt V v i = 22 cos(100tt - t/6) A.x,y l phn t g? A: R v CB: R v LC: L v CD: A v B Cu 11:Mch in X cha hai trong ba phn t (R,L,C). Biu thc u trong mach l u = 30cos( 100tt + t/3) V; v biu thc i = 2cos( 100tt + t/6). Hy xc nh l phn t g? A: R v CB: R v LC: L v CD: A v B Cu 12: Mch in X cha hai trong ba phn t (R,L,C). Biu thc u trong mach l u = 30cos( 100tt + t/3) V; v biu thc i = 2cos( 100tt - t/6). Hy xc nh l phn t g? Xc nh tng tr ca mch? A: L v C; Z = 15 B: L v R; Z = 15 C: R v C; Z = 30 D: L v C v 40 Cu 13:Mch in X cha xc nh, qua thc nghim thy c dng in trong mch i = 5cos( 100tt) A, v hiu in th trong mach u = 100cos( 100tt) V. Mach X c th gm phn t g? A: in tr thunB: Mch RLC cng hngC: C A v BD: Khng c p n ng. Cu 14:on mch X ch gm t in, dng in trong mch chm pha hn u mt gc t/3 cn ghp ni tip X vi Y. Xc nh phn t Y. A: LB: R,LC: RD: R,C Cu 15:Mch X ch c in tr, dng in trong mch nhanh pha hn u th c th ghp vo X nhng phn t no sau y. A: CB: L,C trong ( Z L> Z C)C: L,C trong ( Z L< Z C)D: p n A,C ng Cu 16:Mch X c hai phn t, u nhanh pha hn i, Hi X l nhng phn t no? A: R,LB:R,CC: RD.Khng c p n Cu 17:Mch X c hai phn t, u nhanh pha hn i, Ghp X vi Y th thy trong mch c biu thc i = u/Z. Hy xc nhphn t c th c ca Y? A: CB: R,CC: R,LD: A,B ng Cu 18:RLC ang c u chm pha hn i, trong mch xy ra hin tng cng hng th cn ghp thm vo mch trn on mch X, Xc nh cc trng hp c th c ca X? A: LB: R,LC: RCD: A,B ng Cu 19:Mch in X c hai phn t ( trong ba phn t R,L,C). mc mch in trn vo mng in c u = 50cos( 100tt) V th thy dng in trong mch c biu thci = 2cos( 100tt + t/6)A.-Xc nh gi tr cc phn t trong mch?A: R = 12,53 ; Z L = 12,5 B: R = 12,5 ; Z L = 12,53 C: R = 12,53 ; Z C = 12,5 D: R = 12,5 ; Z C = 12,53-Tnh cng sut trong mch khi ? A: 50 WB: 502 WC: 503 WD: 100W Gv: Nguyn Hng Khnh _ HKP PHNG PHP GII BI TP DNG IN XOAY CHIU LTHDi ng: 09166.01248 Email: Khanhcaphe@gmail.com Gio Dc Hng Phc - Ni Khi u c M! HP 44 Cu 20:Mch in gm hai phn t L,C trong L = 1/tH v C = 10-3 /6tF. Mc ni tip on mch trnvi phn t X( X ch cha mt phn t) v mc vo mng in u = 50cos( 100tt + t/3)V,th thy cng sut trong mch l 25W v ang c hin tng cng hng xy ra. Xc nh cc phn t X trn v tm gi tr ca n? A: L = 0,4/tHB: 10-4 /(4t)F C: 10-3 /4tFD: A hoc C Cu 21:Mch in X c hai phn t ( trong ba phn t R,L,C). mc mch in trn vo mng in c u = 50cos( 100tt th thy dng in trong mch c biu thci = 2cos( 100tt - t/3)A.- Xc nhgi tr cc phn t trong mch? A: R = 12,5 ; Z C = 12,53 B: R = 12,53 ; Z C = 12,5 C: R = 12,53 ; Z C = 12,5 D: R = 12,5 ; Z L = 12,53 - Tnh cng sut trong mch khi ? A: 25WB: 252 WC: 30WD: 302 W Cu 22: Mt cun dy c R o v t cm L c mc vo ngun in xoay chiu c u = 2002 cos( 100tt) V. Th I = 5A v lch pha so vi u mt gc 60o . Mc ni tip cun dy vi on mch x th I 2 = 3A v lch pha gia hai u cun dy vi hiu in th hai u on mch x l 90o . 1Tnh Ro v Z L? A: R = 20 ; Z L = 20 B: R = 203; Z L = 20 C: R = 20 ; Z L = 203 D: R = 30 ; Z L = 203 2P tiu th trn on mch x? A: P = 415,7WB: 480 WC: 253WD: 356W 3Bit x gm hai trong ba phn t R,L,C mc ni tip. Tnh gi tr ca hai phn t ? A: R = 46 ; Z C = 26,6 B: R = 26,6 ; Z C = 46 C: R = 50 ; Z L = 26,6 D: R = 46 ; Z L = 26,6 Cu 23:Mch RLC mc ni tip vo mng in xoay chiu c hiu in th khng i. Bit Z L = 80 , phng trnh hiu in th l u = 2002 cos( 100tt + t/6) V v phng trnh dng in qua mch l i = 22 cos( 100tt + t/3) A. Tm gi tr ca in tr v in dung? A: R = 503 ; Z C = 40 B: R = 50; Z C = 30 C: R = 603 ; Z C = 40 D: R = 503 ; Z C = 130 Cu 24:Mch RLC mc ni tip c gi tr dung khng gp i gi tr cm khng. V mch in c lch pha gia u v i l (- t/3) rad. Tm pht biu ng? A: Z L=3 RB: Z C =3 RC: R =3 Z L D: R =3 Z C

Cu 25: Cho mch RLC trong R = 2Z L = 23 Z C th pht biu no sau y l ng? A: u v i trong mch cng pha vi nhauB: u trong mch nhanh pha hn i gc t/3 rad C: i trong mach nhanh pha hn u gc t/4 radD: u nhanh pha hn i gc t/4 rad. Cu 26:Mch in AB mc ni tip, gi M l im trn mch in AB. Ngi ta o c hiu in th gia hai u AM c biu thc u = 2002 cos( 100tt + t/6) V v hiu in th gia hai u on mch MB c biu thc u = 2002 cos(100tt - t/2) V. Tm biu thc ca on mch AB. A: u = 2002 cos(100tt)VB: u = 200cos(100tt)VC: u = 200cos(100tt - t/6)V D:u=2002cos(100tt- t/6)V Cu 27:Cho on mch xoay chiu gm RLC, gi M l im gia RL v C. Trong R = 50 , cun cmthun c L = 0,5/t H, f = 50 Hz in p u AMv u AB lch pha nhau gc t/2. in dung ca t in l: A. 10-4 / 5tFB: 2.10-4 / tFC: 10-4 / 2tFD: 10-4 / tFCu 28:Mt cun dy thun cm, c t cm L = 2tH mc ni tip vi mt t in C = 31,8F . Bit in pgia 2 u cun dy c dng u = 100cos (100 t6tt+ )(V). Biu thc in p gia 2 u t in l A: u = 50cos ( 1005t6tt ) ( V) B: u = 50 cos ( 1005t6tt+ ) ( V) C:u=100 cos (100 t3tt )(V) D: u=100 cos (100 t3tt+ )(V)on mch AB theo th t gm cun dy thun cm, in tr thun R v t in mc ni tip nhau, im M ni gia cun dy v intr R, im Nnigia intr Rvit in. Hiuinth camch inl:u =U2 cos 100t (V).Cho bit R=30O UAN=75 V, UMB= 100 V; UAN lch pha /2 so vi UMB. Cng dng in hiu dng l: A: 1A.B: 2A.C: 1,5A.D: 0,5A. Cu 29:Cho on mch in xoay chiu gm cun dy c in tr thun R, mc ni tip vi t in. Bit hiu in th gia hai u cun dy lch pha nhau t/2 so vi hiu in th hai u on mch. Mi lin h gia in tr thun R vvi cm khng Z L ca cun dy v dung khng Z C ca t in l: A: R2 = Z C ( Z L - Z C )B: R2 = Z C( Z C - Z L)C: R2 = Z L( Z C - Z L)D: R2 = Z L( Z L - Z C) Cu 30:Mt onmch in xoay chiu gm R v C mc ni tip c hiu in th hai u mch c biu thc u = 100cos 100tt V, b qua in tr cc dy ni, Bit cng dng in trong mch c gi tr hiu dng l 1A v sm pha t/3 so vi hiu in th hai u mch. Gi tr ca R v Z C l: Gv: Nguyn Hng Khnh _ HKP PHNG PHP GII BI TP DNG IN XOAY CHIU LTHDi ng: 09166.01248 Email: Khanhcaphe@gmail.com Gio Dc Hng Phc - Ni Khi u c M! HP 45 A: R = 252 ; Z C = 256 B: R = 206 ; Z C = 256C: R = 202 ; Z C = 256 D: R = 25 ; Z C = 256Cu 31:Mach RC c in tr 50 , mc mch in vo dng in c tn s f = 50 Hz, dng in trong mch nhanh pha t/3 so vi hiu in th trong mch. Tm gi tr dung khng khi ? A: 253 B: 50 C: 503 D: p n khc Cu 32:Mch RL c R = 100 , c mc vo mch in 50V -50 Hz, thy hiu in th trong mch nhanh pha hn dng in t/6. Tm cng sut ca mch. A: 30 WB: 18,75WC: 50WD: 57,5W Cu 33:Trong mch RLC, hiu in th hai u on mch v hai u t in c dng u = U o cos( et + t/6) v u C = U oC cos( et - t/2) V th biu thc no sau y l ng? A: - R/3 = ( Z L - Z C)B:3R = ( Z C - Z L)C:3R = ( Z L - Z C)D: R/3= ( Z L - Z C) Cu 34:Cho mch in gm LRC mc theo ng th t, trong C c th thay i c, L = 1/tH, R = 100, f = 50Hz. Gi M l im gia L v RC. Tm gi tr ca C u AM v u AB lch pha gc t/2. A: 10-4 /tFB: 10-4 /2t FC:3/t.10-4 FD: 2.10-4 /tF Cu 35:Cho mch in gm cun dy c in tr thun R, h s t cm L mc ni tip t in c in dung C = 15,9 F. Hiu in th gia hai u ca mch l u = 200 sin100tt V. Hy tm R v L ca cun dy. Bithiu in th gia hai bn cc t C c biu thc u C = 2002 sin( 100tt - t/4) V. A: L = 0,318H; R = 200 .B: L = 0,318H; R = 150 C: L = 0,15,9H; R = 100 D: L = 0,318H; R = 100 Cu 36:Mt on mch in xoay chiu gm mt t in c dung khng ZC = 200 v mt cun dy mc ni tip. Khi t vo haiu on mch trn mt in p xoay chiu lun c biu thc u = 1202 cos(100t + t3 )V th thy in p gia hai u cun dy cgi tr hiu dng l 120 v sm phat2so vi in p t vo mch. Cng sut tiu th ca cun dy l A: 72 W.B: 240W.C: 120W.D: 144W Cu 37:t vo hai u mch in cha hai trong ba phn t gm: in tr thun R, cun dy thun cm c t cm L, t in c in dung C mt hiu in th xoay chiu n nh c biu thc u = U0coset(V) th cng dng in qua mch c biu thc i = I0cos(et - /4) (A). Hai phn t trong mch in trn l: A: Cun dy ni tip vi t invi ZL = 2ZC.B: Cun dy ni tip vi t in vi 2ZL = ZC. C: in tr thun ni tip vi cun dy vi R = ZL.D: in tr thun ni tip vi t in vi R = ZC. Cu 38:tinpxoaychiuvohaiuonmchRLCnitipthccinphiudngcquanh 3 UR=3UL=1,5UC. Trong mch cA: dng in sm pha 6t hn in p hai u mchB: dng in tr pha 6t hn in p hai u mch. C: dng in tr pha 3t hn in p hai u mch.D: dng in sm pha 3t hn in p hai u mch. Cu 39:t in p xoay chiuu U 2cos( t)V = evo hai u on mch RLC khng phn nhnh c quan h gia cc in p hiu dng l U=2UL=UC th A: dng in tr pha 3t hn in p hai u mch.B: dng in tr pha 6t hn in p hai u mch. C: dng in sm pha 6t hn in p hai u mch.D: dng in sm pha 3t hn in p hai u mch. Cu 40:Chomch innh hnhv 050 3 R= O, 50L CZ Z = = OAMU v MBUlch pha 750. in tr R c gi tr l B L, R0 RC M A A: 25 3OB:50OC:25OD:50 3O Cu 41: Cho mch in gm in tr R = 100O, cun dy thun cm L =1t H, t in c C= 12t .10-4F . Hiu in th hai u on mch c tn s l 50 Hz. Pha ca hiu in th hai u on mch so vi hiu in th gia hai bn t l A: Nhanh hn t4 B: Nhanh hn t2 C: Nhanh hn t3 D: Nhanh hn3t4

Cu 42:mchinR=100 3 O; 410C F2=t.KhitvoABmtinp xoay chiu c tn s f=50Hz th uAB v uAM lch pha nhau 3t. Gi tr L l: Gv: Nguyn Hng Khnh _ HKP PHNG PHP GII BI TP DNG IN XOAY CHIU LTHDi ng: 09166.01248 Email: Khanhcaphe@gmail.com Gio Dc Hng Phc - Ni Khi u c M! HP 46 A: 3L H =tB: 1L H =tC: 2L H =tD: 3L H =t Cu 43:mchinxoaychiuR=80O; 310C F16 3=t; AMu 120 2cos(100 t )V6t= t+ ; uAM lch pha 3t vi i. Biu thc in p hai u mch l: A: ABu 240 2cos(100 t )V3t= t+ B: ABu 120 2cos(100 t )V2t= tC: ABu 240 2cos(100 t )V2t= t+ D: AB2u 120 2cos(100 t )V3t= tCu 44:C 2 cun dymc ni tip vi nhau,cun 1 c t cm 1L ,in tr thun 1R ,cun 2 c t cm 2L ,in tr thun 2R .Bit1L2R = 2L1R.Hiu in th tc thi 2 u ca 2 cun dy lch pha nhau 1 gc: A:t /3 B:t /6 C:t /4D: 0 Cu 45:Mch in AB gm cun dy c in tr trong r v t cm L, mc ni tip vi t in C. Gi UAM l hiu in th haiu cun dy v c gi tr U AM= 40 V, U MB = 60V hiu in th u AMv dng in i lch pha gc 30o . Hiu in th hiu dng U ABl: A: 122,3VB: 87,6VC: 52,9VD: 43,8V Cu 46:t in p xoay chiu c tr hiu dngU 100 3 V =vo hai u on mch RLC c L thay i. Khi in p hiu dng ULMax th UC = 200V. Gi tr ULMax l A. 100 VB. 150 VC. 300 VD. p n khc.Cu 47:t in p u = U 2 cost vo hai u on mch RLC ni tip. Trong U, e, R v C khng i. iu chnh L in p hiu dng trn L t cc i. Chn biu thc sai A: 2 2 2 2R L CU U U U = + + B: 2 2L C LU U U U 0 = C: 2 2L C CZ Z R Z = + D: 2 2CLU R ZUR+=

Cu 48: Chomch RLC mc ni tip vi hai u AB, Gi M l im gia RC v L. Gi U RC= U AM= U AB= 100V; u MBvu AMlch pha 120o . Hiu in th hiu dng U MBl: A: 80VB: 100VC: 50VD: 120V Cu 49:Mch in AB gm cun dy c in tr trong r v t cm L, mc ni tip vi t in C. Gi UAMl hiu in th hai u cun dy v c gi tr U AM = 75 V, U MB = 125V v U AB = 100V. lch pha cain p u AM so vi dng in i l A: 37o B: 62o C: 45o D: 72o Cu 50:Cho mch gm c ba phn t l R,L,C, khi ta mc R,C vo mt in p xoay chiu u=200cos(t) V th thy i sm pha so vi u l t /4, khi ta mc R,L vo hiu in th trn th thy hiu in th chm pha so vi dng in l t /4. Hi khi ta mc c ba phn t trn vo hiu in th th hiu in th gia hai u MB c gi tr l bao nhiu? A: 200V. B: 0 V. C: 100/ 2V. D: 100 2V.Cu 51:Cho mt on mch RLC, t vo hai u mch mt hiu in th xoay chiu th thy hiu in th hai u cun dy vung pha vi hiu in th hai u mch, v khi hiu in th gia hai u R l 50V. Hiu in th hiu dng gia hai u on mch l:A: U=75(V). B: U=50(V). C: U=100(V). D: U=50 2(V).Cu 52:Biuthchiuinth2umchvcngdnginquamchRLCmcnitiplnltl:u= 200cos(100 t t- t /6) V,i = 2cos(100t t+t /6) A. in tr thun R ca on mch l: A: 50OB: 60O C: 100OD: 200O Cu 53: mch in hp kn X gm mt trong ba phn t n tr thun, cun dy, t in. Khi t vo AB in p xuay chiu c UAB=250V th UAM=150V v UMB=200V. Hp kn X l A: cun dy cm thun.B: cun dy c in tr khc khng. C: t in.D: in tr thun. Cu 54:Hnh v( )ABu U 2 cos 2 ft V = t.Cun dy thun cm c t cm 5L H3=t , t din c 310C F24=t.Ht uNB v uAB lch pha nhau 900 .Tn s f ca AC RLBM Gv: Nguyn Hng Khnh _ HKP PHNG PHP GII BI TP DNG IN XOAY CHIU LTHDi ng: 09166.01248 Email: Khanhcaphe@gmail.com Gio Dc Hng Phc - Ni Khi u c M! HP 47 dng in xoay chiu c gi tr l A: 120HzB: 60HzC: 100HzD: 50Hz Cu 55:Mt on mch in xoay chiu c dng nh hnh v.Bit hiu in th uAE v uEB lch pha nhau 900.Tm mi lin h gia R,r,L,.C A B C r R,LE A: R = C.r.L B:r =C. R..L C: L = C.R.rD:C = L.R.r Cu 56:Mtmchinxoaychiu (hnhv)gm RLCnitipmtin p xoay chiu c tn s f = 50Hz. Bit R l mt bin tr, cun dy c t cm L =1t(H), in tr r = 100. T in c in dung C = 4102t(F). iu chnh R sao cho in p gia hai u on mch AM sm pha 2t so vi in p gia hai im MB, khi gi tr ca R l : CL, rA BRM A: 85O .B: 100O .C: 200O .D: 150O . Cu 57:Cho mt mch in gm mt t in c in dung C mc ni tip vi bin tr R. Mc vo hai u mch in mt hiu in th xoay chiu c tn s f. Khi R=R1 th cng dng in lch pha so vi hiu in th gia hai u on mch mt gc 1. Khi R=R2 th cng dng in lch pha so vi hiu in th gia hai u on mch mt gc 2. Bit tng ca 1 v 2 l 90o. Biu thc no sau y l ng?A: 1 2Cf2 R R=t. B: 1 2R Rf2 C=t. C: 1 22fC R Rt=. D: 1 21f2 C R R=t.Cu 58:Mt on mch gm mt cun dy khng thun cm c t cm L, in tr thun r mc ni tip vi mt in tr R = 40O. Hiu in th gia hai u on mch c biu thc u = 200cos100tt (V). Dng in trong mch c cng hiu dng l 2A v lch pha 45O so vi hiu in th gia hai u on mch. Gi tr ca r v L l: A: 10O v 0,159H.B: 25O v 0,159H.C: 10O v 0,25H.D: 25O v 0,25H. Cu 59:t vo hai u mch in xoay chiu gm mt cun dy v mt t in mc ni tip mt in p xoay chiu n nh c biu thc u =100 6 cos(100 t )(V).4tt+Dng vn k c in tr rt ln ln lt o in p gia hai u cun cm v hai bn t in th thy chng c gi tr ln lt l 100V v 200V. Biu thc in p gia hai u cun dy l: A:du 100 2 cos(100 t )(V)2t= t+ .B:du 200cos(100 t )(V)4t= t+ . C:d3u 200 2 cos(100 t )(V)4t= t+ .D: d3u 100 2 cos(100 t )(V)4t= t+ . Cu 60:Mch R,L,C ni tip c L l cun thun cm. Hiu in th v dng in trong mch c biu thc u = U0cos(100t+ /12)(V) v i = I0cos(100t+/3)(A). Ta s c mi lin h: A: ZL - ZC =1,73RB: ZC ZL =3RC: ZL - ZC =RD: ZC ZL =R Cu 61:Mch in xoay chiu gm in tr thun R =30(O)mc ni tip vi cun dy.t vo hai u mch mt hiu in th xoay chiu u = U2 sin(100t)(V).Hiu in th hiu dng hai u cun dy l Ud = 60 V. Dng in trong mch lch pha /6 so vi u v lch pha /3 so vi uD. Hiu in th hiu dng hai u mch ( U ) c gi tr A: 603 (V). B: 120 (V).C: 90 (V).D: 602(V). Cu 62:Cho mch in xoay chiu nh hnh v, cun dy thun cm. S ch cc vn k (V1), (V2) ln lt l U1 = 80V; U2 = 60V. Bit hiu in th tc thi uAN bin thin lch pha t2 vi hiu in th tc thi uMB. Hiu in th hiu dng hai u in tr thun R l V2 V1 AN LB M C R A: 96VB: 140VC: 48VD: 100V Cu 63:Mt on mch in xoay chiu mc theo th t gm: on AM l cun cm thun, on MN l in tr, on NB l t in. t vo hai u AB mt in p xoay chiu th o c ANU 200(V) = , MBU 150(V) = ng thi uAN lch pha /2 so vi uMB. Dng in chy qua mch li 2cos(100 t)(A) = t . Cng sut tiu th ca on mch l A: 100(W)B: 120(W)C: 120 2(W) D: 240(W) Cu 64:Mch in xoay chiu RLC ghp ni tip, t vo hai u mch mt hiu in th u = U0cos et (V). iu chnh C = C1 th cng sut ca mch t gi tr cc i Pmax = 400W. iu chnh C = C2 th h s cng sut ca mch l 32. Cng sut ca mch khi l: A:200WB: 100 3 W C: 100WD:300W Gv: Nguyn Hng Khnh _ HKP PHNG PHP GII BI TP DNG IN XOAY CHIU LTHDi ng: 09166.01248 Email: Khanhcaphe@gmail.com Gio Dc Hng Phc - Ni Khi u c M! HP 48 Cu 65:Mt mch in xoay chiu R L C trong L thay i c, mc ni tip vo hiu in th xoay chiu c f = 50Hz. Khi 11L L H = =t v 23L L H = =t th h s cng sut mch in u bng nhau v bng12.in tr thun ca mch in l: A.R 300 = OB. 100R3= OC.R 200 = OD.R 100 3 = OCu 66:on mch in gm in tr thun R= 50Omc ni tip vi hp X. t vo hai u on mch mt in p c dng u = U0 cos( 100 t t + ) (V;s) th cng dng in trong mch sm phat /3 so vi in p. Bit hp X ch c cha mt trong cc phn t: in tr thun r, t in C, cun dy L. Phn t trong hp X l A: cun dy thun cm c 3L H2=tB: t in c 42.10C F3.=t C: in tr thun r = 50 3 D: cun dy c r = 50 3v 3L H2=t Cu 67:Chomch in xoay chiu RLCmcni tip, bit R =100 3O ; in p xoay chiugiahai u on mch c dngu U 2.cos100 t(V) = t , mch c L bin i c. Khi L =2/ t (H) th ULC = U/2 v mch c tnh dung khng. ULC = 0 th t cm c gi tr bng A: 12t(H).B: 2t(H).C: 3t(H).D: 13t(H). Cu 68:Mt cun dy c in tr thunO = 3 100 Rv t cm L = 3/H mc ni tip vi mt on mch X c tng tr ZX ri mc vo in p c xoay chiu c gi tr hiu dng 120V, tn s 50Hz th thy dng in qua mch in c cng hiu dng bng 0,3A v chm pha 300 so vi in p gia hai u mch. Cng sut tiu th trn on mch X bng: A:0W 4 B:W 3 9 C:W 3 18 D:W 30Cu 69:Mt mch in gm in tr thun R, cun dy thun cm v mt t in c in dung thay i c mc ni tip. t vo hai u on mch trn mt in p xoay chiu c biu thcu U 2 cos t(V) = e . Khi thay i in dung ca t cho in p hiu dng gia hai bn t t cc i v bng 3U. Ta c quan h gia ZL v R l A: ZL = R3B: ZL =3 RC: ZL =2 2 RD: ZL = 2R Cu 70:Mt on mch RLC mc ni tip c tn s dng in 50 Hz, LZ 20 = O, C c th thay i c. Cho C tng ln 5 ln so vi gi tr khi xy ra cng hng th in p hai u on mch lch phat /3 so vi dng in trong mch. Gi tr ca R l: A: 16/3O B: 163OC: 163O D: 803O Cu 71:Mch in xoay chiu gm in tr R = 100Omc ni tip vi hp kn X cha hai trong ba phn t (in tr thun, cun cm thun, t in). Khi ta mc vo mch mt hiu in th mt chiu U th dng in trong mch l 2 A. Khi mc vo mch mt hiu in th xoay chiu c gi tr hiu dng vn l U sau dng vn k ln lt o hiu in th gia hai u R v X th thy vn k cng ch gi tr 100 3 V v khi dng in lch pha so vi hiu in th hai u mch gc/ 6 t . Hp X cha: A: 0 LR 100 , Z 100 = O = O B: 0 CR 100 , Z 100 = O = OC: 0 LR 50 , Z 50 3 = O = OD: 0 LR 50 , Z 100 = O = OCu 72:Mch in xoay chiu RLC ghp ni tip trong cun dy thun cm c t cm1/ H tt in c in dung C thay i c. Mc mch vo mng in xoay chiu tn s 50Hz. Khi thay i