Dien Xoay Chieu.15535

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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