DIEN XOAY CHIEU HAY

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DNG IN XOAY CHIUDng 1: -Xc inh cc i lng xoay chiu -Vit biu thc u,iCu 1:Cng dng in lun lun sm pha hn in p hai u on mch khi A. on mch ch c R v C mc ni tip. B. on mch ch c L v C mc ni tip. C. on mch ch c cun cm L. D. on mch c R v L mc ni tip Cu 1:Nguyn tc to dng in xoay chiu da A. Hin tng t cm. B. Hin tng cm ng in t. C. T trng quay. D. Hin tng quang in. Cu 2:Dng in xoay chiu l dng in c tnh cht no sau y? Chiu dng in thay i tun hon theo thi gian. Cng bin i tun hon theo thi gian. Chiu thay i tun hon v cng bin thin iu ho theo thi gian. Chiu v cng thay i u n theo thi gian. Cu 3:Chn pht biu ng khi ni v dng in xoay chiu Dng in xoay chiu c cng bin thin tun hon theo thi gian. Dng in xoay chiu c chiu dng in bin thin iu ho theo thi gian. Dng in xoay chiu c cng bin thin iu ho theo thi gian. Dng in xoay chiu hnh sin c pha bin thin tun hon. Cu4:Chn mt trong cc cm t sau in vo ch trng sao cho ng ngha: Cng dng in............. ca dng in xoay chiu l cng d dng in khng i khi qua cng vt dn trong cng thi gian lm to ra cng nhit lng nh nhau. A. Hiu dng B. Tc thi. C. Khng i D. A, B, C khng thch hp Cu 5:Biu thc ca cng dng in trong mt on mch AC l:

1 s i = 5 2cos(100 t + ) A . thi im t = 300 6

cng trong mch t gi tr:: A. Cc i B. Cc tiu C. Bng khng D. Mt gi tr: khc Cu 6:Mt dng in xoay chiu c tn s 50Hz th trong mi giy dng in i chiu my ln ? A. 100 ln. B. 25 ln. C. 50 ln. D. 60 ln. Cu 7 :Chn pht biu sai trong cc pht biu sau y? Khi cng dng in qua on mch ch c in tr R v qua on mch gm in tr R mc ni tip vi mt t C l nh nhau th cng sut tiu th trn c hai on mch ging nhau. Trong mch RC in nng ch tiu th trn in tr R m khng tiu th trn t in.. T in khng cho dng xoay chii i qua. M..Dng in xoay chiu thc cht l mt dao ng cng bc Cu 8 : Chn pht biu ng khi ni v mch in xoay chiu c in tr R: A.Nu hiu in th hai u in tr c biu thc u = U 0 cos(.t + ) th biu thc dng in qua in tr l i = I 0 cost B.Mi lin h gia cng dng in v hiu in th hiu dng c biu din theo cng thc U= I/R C.Dng in qua in tr v hiu in th hai u in tr lun cng pha. D.Pha ca dng in qua in tr lun bng khng. Cu 9 :Mch in gm in tr R. Cho dng in xoay chiu i = I 0 cost (A) chy qua th hiu in th u gia hai u R s: A. Sm pha hn i mt gc

2

v c bin U 0 = I 0 R

B. Cng pha vi i v c bin U 0 = I 0 R

C. Khc pha vi i v c bin U 0 = I 0 R

D. Chm pha vi i mt gc

2

v c bin U 0 = I 0 R

Cu 10 :Trong mch in xoay chiu ch c t in C th dung khng c tc dng A. Lm hiu in th nhanh pha hn dng in mt gc B. Lm hiu in th cng pha vi dng in. C. Lm hiu in th tr pha hn dng in mt gc

2

2

D. lch pha ca hiu in th v cng dng in tu thuc vo gi tr: ca in dung C. Cu 11: Chn pht biu sai? A. Trong on mch ch c cun dy thun cm khng, dng in lun chm pha hn hiu in th tc thi mt gc

2

.

B. Cng dng in qua cun dy c tnh bng cng thc : I 0 =

U 0L ZL

C. Trong on mch ch cha in tr R th cng dng in v hiu in th hai u mch lun lun cng pha nhau.. U D. Cng dng in qua mch in c tnh bng cng thc : I 0 = . R Cu 12: Chn pht biu ng khi ni v mch in xoay chiu ch c cun dy thun cm khng A. Cm khng ca cun dy t l vi hiu in th t vo n. B. Hiu in th gia hai u cun dy thun cm khng chm pha hn dng in mt gc C. Hiu in th gia hai u cun dy thun cm khng nhanh pha hn dng in mt gc

2

2

D. Cng hiu dng ca dng in xoay chiu qua cun dy c tnh bng cng thc I= U.L. Cu 14: Trong on mch xuay chiu ch c cun dy thun cm khng, hiu din th hai u cun cm c biu thc u = U 0 cost th cng dng in i qua mch c biu thc i = I 0cos(.t + ) trong Io v c xc nh bi cc h thc no sau y?

U0 v = - . L U C. I 0 = 0 v = 0. LA. I 0 =

B. I 0 = D. I 0 =

Cu 15: Chn pht biu ng khi ni v mch in xoay chiu c t in A. t in khng cho dng in khng i i qua, nhng cho dng in xoay chiu i qua n. B. Hiu in th gia hai u t in lun chm pha so vi dng in qua t mt gc

U0 v L

= - .2

U0 v L

= .2

2

C. Cng hiu dng ca dng in xoay chiu qua t in c tnh bng cng thc I= U.C. D. C A, B, C u ng Cu 16: Trong on mch xoay chiu ch c t in, hiu in th trn t in c biu thc u = U 0 sin t V th cng dng in qua mch c biu thc y? A.

i = I 0cos(.t + ) , trong Io v c xc nh bi cc h thc tng ng no sauB. Io= Uo.C. v

I0 =

2

U0 v = . 2 C

= 0

C.

I0 =

U0 v = .D. Io= Uo.C. v = 2 C

Cu 17: Chn pht biu ng khi ni v mch in xoay chiu c in tr R: A. Nu hiu in th hai u in tr c biu thc u = U 0 cos(.t + ) V th biu thc dng in qua in tr l

i = I 0costB. Mi lin h gia cng dng in v hiu in th hiu dng c biu din theo cng thc U=I/R C. Dng in qua in tr v hiu in th hai u in tr lun cng pha. D. Pha ca dng in qua in tr lun bng khng. Cu 18:Mch in no di y tha mn cc iu kin sau : Nu mc vo ngun in khng i th khng c dng in nu mc vo ngun

u = 100cos(100 .t )V th c i = 5cos(100 t + ) A 2

A. Mch c R ni tip C B. Mch c R ni tip L C. Mch ch c C D. Mch c L ni tip C Cu 19 Hai cun dy R1, L1v R2, L2 mc ni tip nhau v t vo mt hiu in th xoay chiu c gi tr: hiu dng U. Gi U1v U2 l hiu in th hiu dng tng ng gia hai cun R1, L1 v R2, L2 iu kin U=U1+U2 l: A.

L1 L2 = R1 R 2

B.

L1 L = 2 R2 R1

C. L1 L2 = R1 R 2

D. L1 + L 2 = R1 + R 2

Cu 20Trong mch in xoay chiu khng phnh nhnh RLC th: A. lch pha ca u R v u l

2

B.Pha ca u L nhanh hn pha ca i mt gc

2

C.Pha ca u C nhanh hn pha ca i mt gc

2

D. Pha ca u R nhanh hn pha ca i mt gc

2

Cu 20:Dng in chy qua mt on mch c biu thc tc thi c gi tr: bng 0,5Io vo nhng thi im:

i = I 0cos100 .t ( A) . Trong khong thi gian t 0 n 0,01s, cng

A.

1 2 s; s 400 400

B.

1 3 s; s 500 500

C.

1 2 s; s 300 300

D.

1 5 s; s 600 600 1

Cu 21: Hiu in th gia hai u mt on mch in xoay chiu ch c cun thun cm L =

u = 200 2cos(100 .t + )V (V) Biu thc ca cng dng in trong mch l: 3 5 A. i = 2 2cos(100 t + ) A B. i = 2 2cos(100 t + ) A 6 6 5 C. i = 2 2cos(100 t ) A D. i = 2cos(100 t )A 6 6 Cu 22:Hiu in th xoay chiu u = U 0 cost (V) vo hai cun dy thun cm L th cng dng inchy qua mch cbiu thc l: A.

H c biu thc:

U i = U 0 cos(.t ) A B. i = 0 cos(.t + ) A 2 L 2 U0 U0 cos(.t ) A cos(.t ) A C. i = D. i = L 2 L Cu 22: t hiu in th u = U 0 cost (V) vo hai u t in C th cng dng in chy qua C l: U A. i = I 0 cos(.t ) A (A) vi I 0 = 0 B. i = I 0 cos(.t + ) A (A) vi I 0 = U 0C 2 2 C U C. i = I 0 cos(.t ) (A) vi I 0 = U 0C D. i = I 0 cos(.t + ) A (A) vi I 0 = 0 2 CCu 23:Cho mt on mch in gm in tr R =50 mc ni tip vi mt cun dy thun cm L = hai u on mch mt hiu in th: u

0,5

i = 2cos(100 .t ) A 2 C. i = 2 2cos(100 .t ) AA. in chy qya R l : A. i = 2 2 cos(100 t+

Cu 24:Hai u in tr R = 50 c biu thc hiu in xoay chiu l u = 100cos(100 t+

= 100 2cos(100 .t )V Biu thc ca cng dng in qua on mch l: 4 B. i = 2 2cos(100 .t ) A 4 D. i = 2cos(100 .t ) A 3

H . t

vo

)V th biu thc cng dng

3

)A. D. i = 2

B. i = 2cos(100 t+

3

)A.

C. i = 2cos100 t A.

2 cos(100 t)A.

Cu 25: Hai u cun dy thun cm c L = 0,318H c hiu in th xoay chiu u =200cos(100 t+ cng d dng in chy qua cun dy l: A i = 2cos(100 tC. i = 2cos(100 t-

3

)V . Th biu thc

6

)A. )A.

B. i = 2cos(100 t+ D. i = 2

3

5 )A. 6

2 cos(100 t-

6

)A.

Cu 26:Hai u t in c in dung 31,8 F mt hiu in th u =120cos(100 t+ l: A. i =1, 2cos(100 t-

6

)V th cng dng in chy qua t

3 2 C. i = 1,2cos(100 t)A. 3

)A.

B. i = 1,2cos(100 t+

2 )A. 3D. i = 2cos(100 t+

6

)A.

Cu 27:Cho mch in khng phn nhnh RLC: R = 80 , cun dy c in tr 20 , c t cm L=0,636H, t in c in dung C = 0,318 F. Hiu in th hai u mch l : u = 200cos(100 tin l: A i= C. i =

4

) V th biu thc cng dng in chy qua mch

2 cos(100 t 2 cos(100 t -

4

2

) A. ) A.

B. i = cos(100 t +

2

) A.. 2 cos100 t A.

D. i =

Cu 28: Mt in tr 50 ghp ni tip vi mt cun dy thun cm c t cm mch c biu thc: i =2

1,2

3 67 ,4 67 ,4 A. u =260 2 cos(100 t)V . B. u =260cos(100 + )V 3 180 180 67 ,4 67 ,4 C. u =260 2 cos(100 ) V . D. u =260 2 cos(100 t+ )V 180 3 180A L D C B

2 cos(100 t -

H . Cng dng in chy qua

)(A) th hiu in th hai u mch l:

Cu 29 :Mch RLC nh hnh v : Bit : 100V 100W ; L = uAD = 200 A. 200 C. 200

1

2 sin (100 t +

6

H,C=

50

F ,

)V Biu thc uAB c dng

2 sin (100 t +2 sin (100 t

3

4

)V B. 200 sin (100 t )V D. 200 sin (100 t +

3

4

)V )V

Cu 30:Mch RLC khng phn nhnh, bit R = 40 ; L = uBD = 80 sin (100 t A. 80 C. 80

3

3 100 F H v C = 5

)V (BD chu LC) Biu thc uAB c dng

2 sin (100 t +2 sin (100 t

1 2

4

)V )V

B. 80 sin (100 t

4

)V

D. 80 sin (100 t +

1 2

)V

Cu 31:Mt on mch gm mt t in C c dung khng 100 v mt cun dy c cm khng 200 mc ni tip nhau. Hiu in th ti hai u cun cm c biu thc dng nh th no? A.

u L = 100cos(100 .t + )V . Biu thc hiu in th hai u t in c 6

5 uC = 50 2cos(100 .t )V )V B. uc = 50cos(100 .t 3 6 7 )V C. uC = 50cos(100 .t )V D. uC = 50cos(100 .t + 6 6Cu 32:Cho cun dy c in tr trong 30 t cm mch l: u = 60 3

2 H mc ni tip vi t in c in dung C, hiu in th hai u 52 V th in dung ca t in l : 5

2 cos100 t(V) .Khi hiu in th hiu dng hai u cun dy l 50

A.C=

Cu 33Mch nh hnh v uAB = 120

10 .10 3 F. F B. C = 7

7

C. C = A

10 F D. Mt gi tr: khc 7L M C B

2

2 cos100 tV Dng vn k c in tr rt ln o gia A v M th thy n ch 120V, v uAM nhanh pha