Bổ trợ kiến thức vật lý

T

"

^—

5 A^T"

CHU VAN BIEN

Gi^o vien chuong trinh bo tro Itien thurc V$t li 12,
kenh yffZ - Dai Truy^n hinh Viet Nam

Bo tra hion IMi « i i

LUYEN m DAI HOC IKEN KENHWi

PHAN

LOAI VA

fHUONG PHAP GlAl CAC BAI

TOAN

CO BAN, DIEN HINH, HAY, LA VA KHO.
Phan i!:

Dltn HOW CHIEU

• Danh cho ttn sinh lOp 12 On tap va thi Bai hqc, Cao dang.

V' 0 Blen scan theo nOl dung va cau tnic 6& tN ciia BO GD E DT,

1 ,

HA

HOI

NHA XUAT BAN DAI HOC QUOC GIA HA NQI


Cty TNHH mv

C h u ae 1 .

C h u d e 1.

B A I T O A N L I E N Q U A N D E N THCJl G I A N

3

1) Q u a n he gia tri hieu dung

12

B A I T O A N L I E N Q U A N D E N D I E N LLfONG

19

BAI T O A N LIEN Q U A N DEN M A C H RLCNOI TIEP

23

BAI TOAN LIEN QUAN DEN BIEU

37

D I E N PHLfC
DIEN

VA DIEU KIEN LECH PHA

47

B A I T O A N L I E N Q U A N D E N C O N G S U A T vA

H ESO CONG SUAT

BAI TOAN LIEN QUAN DEN GIAN D OVECTO
DOI CAU TRUC

M a c h chi c6 R t h i u va i cung pha va R = ^ =
•

••'

''^v^

'f..v

104
132

II; ' • • •

~ "
i

' ,

= (oL =

M a c h chi c6 L t h i u som h a n i la

M a c h chi c6 C thi u tre h o n i la — va Z^- =

1

Uo
lo
Uo

(oC

lo
2

D o i v o i mach chi c6 L , C thi u v i i o n g pha v d i i nen

In

/

u

A2

U„

V i du 1 : D a t vao hai dau m o t cuon cam thuan L mot dien ap xoay chieu c6 gia
hieu d u n g qua L la 2,4 A . De c u o n g d o hieu d u n g qua L bang 3,6 A t h i tan
so

CLia

d o n g dien phai bang

A . 75 H z .

.

U

U

Chude2.
1=

MAY DIEN

BAI TOAN LIEN QUAN DEN M A Y PHAT DIEN XOAY CHIEU

1

t r i hieu d u n g U k h o n g doi va tan so f thay d o i . K h i f = 60 H z t h i c u o n g do

MACH,

B A I T O A N L I E N Q U A N D E N ClJC T R I

1:

•

58
71

H O P K I N , G l A T R I TL/C THCfl

::

DI^N

Phuong phdp giai

B A I T O A N L I E N Q U A N D E N M A C H C H I C O R, C H I C O L , C H I C O C

BAI TOAN LIEN QUAN DEN THAY

Vipt

BAI TOAN LIEN QUAN DEN MACH CHI C6 R, CHJ C6 L, CHJ C6 C

MACH DIEN

B A I T O A N L I E N Q U A N D E N C O N G HUCJNG

MACH

DWH Khang

_

B. 40Hz.

C. 25 H z .

D. 5 0 V 2 H z .

I , =•
I. =

1 P H A .. 200

MI- v '

Ir
^""^'^ ^ f2 = f, .1L = 6 0 . ^ = 40 ( H z ) => C h o n B.
U
I2

3,6
"If'a'l 0'.' IV^

27:f7L

B A I T O A N L I E N Q U A N D E N M A Y PHAT D I E N X O A Y C H I E U 3 PHA...

211

BAI TOAN LIEN QUAN DEN DONG C ODIEN

215

do hieu d u n g qua mach la 2A. Neu mac tu vao nguon u = Ucos(1207tt + 0,5::)

BAI TOAN LIEN QUAN DEN M A Y BIEN AP

225

(V) thi c u o n g d o hieu d u n g qua mach la bao nhieu?

BAI TOAN LIEN QUAN DEN TUYEN

237

A. 1,2N/2A.

TAI DIEN

B A I T A PD I N H T I N H

B A I T A PD I N H L U O N G

V i du 2 : M o t tu dien k h i mac vao nguon u = uV2

,

286

' C. V2

""'XHuongdan

253
^,„rn:.-.:v;.r.r::.::;:::.T;::::.:^^^
,

B . 1,2A.

cos(100Kt + 7t) (V) thi cuong

A.

D . 3,5 A .

••*'-,''-:''>:^'<':':<-'y .z,:^''-:'''-<':•''

I = - ^ = coC.U^j;'="'^y; = . k = ^ ^ I , = l , 2 V 2 ( A ) = > C h o n A .
Zc

[l2=(02CU2

Ij

(0|U,

V i d u 3: D o a n mach dien xoay chieu tan so f i = 60 H z chi c6 m o t t u dien. N e u
tan so la h thi d u n g k h a n g cua tu dien tang them 20%. T a n so
A . f2 = 72 H z .

B.

f2 = 50 H z .

C . f2 = 10 H z .

D . f2 = 2 5 0 H z .


Cty TNHHITTVDVVHKhang
BS trg kiSn thiic V$t If LTBH

trBn kenh

VTV2. t^p 2 - Chu V^n Bi&n

Huong
- ? C 2 . ^ A. = 1 0 0 % + 2 0 % = 1,2 => f2 =
ZQI

(2

Huang

•'1/ ••••

= 50(Hz)

Chon B.

C,
Cn=-

Chuy:
1)

Dien dung cm

tu dien vhdng

tinh theo cong thiec: C =

1)

nen

S

=

^

9,10

qua tu I =

_U_

do hieu dung

tu).

=^Zr

khong

doi thi dien dung cua tu C =

1

'

^ — = ZCQ nen cuang

song

+ C 2 = ( 1 - X + ex)Co .

"

' .

20

7

g.s

_ 20C0

9.10^.47i.0,3.d

2)

khi

vd cdc yeu

tokhdc

1 = ^ . 1 , , = ^ . 6 , 8 = 8 ( A ) r:^ C h o n B .
1)'-'

Q u a n he gia tri tuc thoi

{A.}S

M a c h c h i c6 R t h i u v a i c i i n g p h a n e n R = — =

= 'T • '

9.10\47r(l-x)d

T.

khong

-X

(1-x)

9.10

S

tiep:
X

ES

Cn

M a c h c h i c6 L t h i u s o m p h a h o n i la n/2 n e n Z L = coL = —- = — ^ ^ ^

1

'

i = IQ C O S cot

M

.47rxd

u = U Q C O S cot + —

2,

Co-

u

+

Jo;

-I.
X + E(1 - x)

i = I() cos cot
1

V i d u 4: M o t t u d i e n p h a n g k h o n g k h i d u g c n o i v a o n g u o n d i e n x o a y c h i e u t h i
c i r o n g d o h i e u d u n g q u a m a c h la 5,4 A . N e u n h i i n g h a i p h a n ba d i e n t i c h
cac b a n t u n g a p v a o t r o n g d i e n m o i l o n g (c6 h a n g so d i e n m o i e = 2) v a

—

= 1<

1
= —

COC

D . 9,0 A .

= U72

u
Uo
u
= — = — ^ —
I

In

2

2

+

u

= 1<

Uo = uV2|:;2

cac
Do'i vc^i m a c h c h i c6 L , C t h i u v u o n g p h a v o i i n e n

y e u t o k h a c k h o n g d o i t h i c u o n g d o h i e u d u n g q u a t u la
C. 10,8 A .

= U() s i n cot
u = U() cos c o t - 2y

,,.

In

Un

:
M a c h c h i c6 C t h i u t r e p h a h o n i la n/2 n e n

do hieu dung qua mqch luc nay Id ] ' = u C U = •

B. 8 , 1 A .

= - U Q s i n cot

I

2

2

1

E

E(1-X)

17

C i + C ,

.a

3

^20^

Q.C2

CintC2

be day bang x phan tram be'

dot thi bo tu C gom hai tu Ci, Ci ghep noi

A . 7,2 A .

=

.

y S >KOO [ A T O - U - u u ' . ;

dan

17

.'.,1'n<<'-ti

Neu ghep sdt vdo mot bdn tu mot td'm dien moi c6

:+

c

9.10'^.47:d

D . 7,2 A .

_ lOCo

9.10\47i.0,7d

^
=>Zr

qua mqch h'lc nay Id V = c o C U = (1 - x + 8 x ) I .

hang so dien moi sco

S

s
khong doi thi bo tu C gom hai tu Ci, Ci ghep

C. 10,8 A .
Huang

„
EXS
Ci =•
•= ( l - x ) C o , C 2 = • = ExCn
9.10^47id
9.10\47td

=> c =

Chon D.

v,^f .

„;;,,v

B.8,0A.

(l-x)S

C-1^2
,C,

•

-•U ' i j l '

so dien moi s) vd cdc yeu tokhdc

day cua lop khong

,

= 9,0(A)

d a y 0 , 3 d c6 h a n g so d i e n m o i e = 2 t h i c u o n g d o h i e u d u n g q u a t u l a

I ' = coCU = EI .

do hieu dung

3

A . 2,7 A .

And

9.10

hang

Cwang

5

= ^.5,4
3'

do hieu

New nhiing x phan tram dien tich cdc bdn tu ngdp vao trong dien moi long (c6

Cwang

5

3::^ I =

9.]0^47rd

m a c h l a 6,8 A . D a t v a o t r o n g t u d i e n v a sat v a o m o t b a n t u m o t t a m d i e n

= COCQU .

yeu tokhdc

C =

- ^ l ^ ^ C = C i + C 2 = - C0

k h o a n g d d u o c noi vao n g u o n dien xoay chieu t h i c u a n g do hieu d u n g qua

cdc bdn tu ngdp vao trong dien moi long (c6 hang so dien moi s) va cdc

song:

3

V i d u 5: M o t t u d i e n p h a n g k h o n g k h i c6 h a i b a n s o n g s o n g each n h a u m o t

chay

.4jid

Neii nhung

^

= ^co
3

moi

dung qua tula

9.10^.47td

C, =

tu la ichong khi thi ZQ = 1

va cwong

=

.47rd ,,

each giua hai ban tu va S la dien tich doi dien gifm cdc ban

Khi chat dien moi trong

'

9.10^ .47rd

(s Id hang so dien

^
9.10

moi, d la khodng

dan

dan

1,2

VIft

1

+

U

luoj

= 1


Ba trg kiSn

thurc

V^t li LTDtl

:i=0<=>u = ±U

tren

henh

VtV2.

t^p 2 - Chu Vdn

Bien

Chu y: Hop kin X chi chi'ra mot trong 3 phan tit la R hoac C hoac L. Dat vao hai dau

(Do thi quan he i i , i la d u o n g clip).

[u = 0 <=> i = ±I()

hop X mot dien dp xoay chieu thi dien dp tren X va ddng dien trong much a thai
diem t| CO gia tri Ian luvt Id i j , u^ vd a thai diem t2 W i 2 , U2 . ,

V i d u 1: ( D H - 2 0 n ) Dat dien ap u = uV2cosa)t vao hai dau m o t tu dien tiii
c u a n g do d o n g dien qua no c6 gia t r i hieu d u n g la I . Tai thoi d i e m t, dien ap

Neil ^

= ^^a

,„ ,

thiX = R = a.

a hai dau tu dien la u va c u o n g do d o n g dien qua no la i . He thuc lien he
*

giua cac dai l u o n g la
,

i^

U^

A. - ^

+

-T-

T2

1

= -.

^
U^
i^
'
B. —^ + - ^ = 1 .

A

T2

U2

J2

Huattg

u = U\/2 coscot
i=lN/2

_

C.
dan

i^

U^

— 5 - + -:5^2
j2

,

y2

— = %/2 coscot
U
= -I\/2 sincot

cos 0)t

V i d u 2: Dat vao hai dau doan

^ u2
D. ^
+

= 2.

2

i2

1

-5- = - .
j2
2

-2
+ V = 2 ^ Chen C.

(Dexdc

dinh dwgc L iiay C thi nen Iwu y: Neu f tang thi Zi tdng nen I gidm con

ZQ gidm nen I tang).
V i d u 4: M o t hop X chi chua m o t trong 3 phan t u la dien t r o thuan hoac tu dien
hoac cuon cam thuan. Dat vao hai dau hop X m o t dien ap xoay chieu chi c6
tan so f thay d o i . K h i f = 50 H z t h i dien ap tren X va d o n g d i e n trong mach 6
thoi d i e m ti c6 gia trj Ian l u g t la: i j = l A , U j = 100

J = - N / 2 sincot
chi c6 cuon cam thuan m o t dien ap xoay

mcich

Nguvc Igi nujch chi c6 L hoac C.

i,=

A , U2 = lOOV. K h i f = lOOHz thi c u a n g d p d o n g dien hieu d u n g

chieu u = UdCOslOOTit (V). Biet gia trj dien ap va c u o n g do d o n g dien tai thai

t r o n g mach la 0,5 V2 A . H o p X chua

diei-n t^ la u^ =50^

A. dien t r o thuan R = 100 Q.

i2

=-^/3

(V),

-Jl

(A) va tai thoi d i e m t2 la U2 = 50 (V),

( A ) . Gia t r i Un la

A.50V.

C50V3V.
Huang

! j ,
2
3
^0

I

^0

C. t u dien c6 d i e n d u n g C = IO-VTI (F).

D . IOOV2 V.

D. tu dien c6 dien d u n g C = 100 ^3 /TI (F).

dan

Huong

2.2500 _ ^
fUo=100(V)
2500 ,
+ —=^ = 1

I„=2(A)

— C h e n B.

...

.y..,, , ,„

tii'VidnmpiS

V i d u 3: Dat vao hai dau m o t cuon cam thuan c6 do t u cam 0,3/;: (H) m o t dien
ap xoay chieu. Biet dien ap c6 gia trj tuc thai 60-J6 (V) t h i d o n g dien c6 gia
trj tuc t h o i V 2 (A) va k h i dien ap c6 gia t r i tuc t h a i 60>/2 (V) t h i d o n g dien
CO gia t r i tuc t h o i %/6 (A). H a y tinh tan so cua d o n g dien.
A.

B. 5 0 ( H z ) .

120 (Hz).

' ' •
360.6

44=:> Z L = 2nfL =

6

360.2

'

C. 100 (Hz).
Huang

=1
,

— +— ^ =1

dan

In

I

dan

4+4=1

fUo=200
10000

i.4=i

= 1

Wf^

"""lo =2=>I = V 2 ( A )

= 120V2

Io-2^/2

= 60 ^ f = lOO(Hz) => Chon C.

t

K h i tan so tang gap d o i neu la tu t h i d u n g khang g i a m 2 Ian nen d o n g hieu
d u n g tang 2 Ian, tuc la F = 2 1 = 2 V 2 A . N h u n g theo bai ra F = 0,5 V 2 A = 1/2
nen X = L sao cho:
Z , =2niL

50

=-

imi

i'"

Uo _ 200
^0

2

7t

L = i(H)=>ChonB.

V i d u 5: (DH-2010) Dat di§n ap u = Uocoscot vao hai dau cuon cam thuan c6 do
t u cam L t h i c u a n g do d o n g dien qua cuon cam la

Uo

U

U,

D . 60 ( H z ) .

(I

C

rJl_

1 -^nnan
30000

•2

•

on

' '"

B. cuon cam t h u a n c6 do t u cam I/TT (H)

>

B.IOOV.

V, 6 t h a i d i e m t2 t h i :

n
A . i = HLcos
a)t + —
coL
C . i = - ^ cos
coL

B. i =

2.

(ot--

n
2

D. i =
Huang

dan

V i mach chi c6 L t h i i tre pha h o n u la n/2 nen

(OLN/2

cos

7t

a)t + —
2.
7t

cos c o t - COL V 2
2J.


Bo trfi kien thijrc V,jt li I. roil

1 = —^cos cot

iren kcnh

VTV2. t^p 2 - Chu V^n

coL-cos

2

Blen

Chu y: Mach ^om L ndi tiep voi C thi dien dp giim hai dau doqn mach u = ui, + uc

•Chon C.

2

Vi du 6: Dat dien ap u = Uocos(1207Tt - TT/4) (V) vao hai dau mgt tu dien thi von
kenhiet (c6 dien tro rat Ion) mac song song voi tu dien chi 120^/2 (V), ampe
kenhiet (c6 dien tro bang 0) mac noi tiep voi tu dien chi 2
( A ) . Chon ket
luan diing.
,i' A . Dien dung ciia tu dien la l/{7,2n) (mF), pha ban dau ciia dong dien qua
tu dien la n/4.
J B. Dung khang cua tu dien la 60 Q, pha ban dau ciia dong dien qua tu dien
n';

la

= 71/2.

. v h

r.. ..nM'.

Wvrl

D. Dien ap cue dai giira hai dau tu dien la 120 y/l (V), dong dien cue dai qua
tu dien la 2 V 2 ( A ) .
Huong dan
Dien dung tu duoc xac dinh tir
=— =
<=> ^
"
^ coC I A 1207rC

I20V2
2V2

=i.C=

V i du 8: Mot doan mach mSc noi tiep gom: tu dien eo dung khang Z c va cuon
cam thuan c6 cam khang Z i , = 0,5Zc. Dien ap giira hai dau tu:
uc = 100eos(1007it + 7t/6) V. Dien ap giiia hai dau doan mach la:
A . u = 200eos(1007it - 57t/6) V.
• •' B. u = 200cos(100Txt - 7r/3) V.
C . u = 100eos(1007it-571/6) V.
D. u = 50cos(1007it + 7:/6) V.
Huong dan
,
1+:

•

|«~.-

=

thi du'a vao he thi'fc \

V i du 7: Do thj bieu dien cuong do tuc thoi cua dong dien xoay chieu chi c6
cuon cam thuan c6 cam khang ZL = 50 Q o hinh ve ben. Viet bieu thue dien
ap tuc thoi giira hai dau cuon cam.
' " hi,;: i ( A )
A . u = 60cos(507it/3 + 7t/3) ( A ) .
B. u = 60sin(1007rt/3 + n/3) ( A ) ,
C. u = 60eos(507it/3 + n/6) ( A ) .
D. u = 30cos(507rt/3 + Tt/3) ( A ) .

hoac Uo=IoZc

Mach chi c6 C thi i sdm pha hcfn u Id K/2.
Mach chi c6 L thi i tre pha hcfn u Id n/2.
••1

2) Neil cho

ii;i2
ui;u2

thi dim vao 2 he thuc

/.I

44Uo=?
T2

TT2

(I

J__Uo

Mack chi c6 C thi i sdm pha hcfn u la TZ 12 vd ZQ =
coC
Mach chi coLthii

tri pha hem uldn/2vdZi=(dL

Huong dan

5071

• \%

-n,.:,,

T

•

\

Vi mach chi eo L thi u som pha han i la 7t/2 nen
507rt

71 71

• CO = ?.

In

150 V thi cuong do dong dien trong mach la 4 A . Bieu thuc ciia cuong do
27t

i = — den i = Old — =
= 0,01
2
12 12co
,

co = ?.

dien CO dien dung 0,2/7t (mF). 6 thoi diem dien ap giua hai dau tu dien la

= — ycidang.dive i = 0nernp = —
2.
3

Thdi gian ngdn nhdt ditii

=

IQ

V i du 9: (DH-2009) Dat dien ap u = Uocos(1007rt - 7t/3) (V) vao hai dau mot tu

i = IQ cos (cot + cp) = 1,2 cos (cot + cp)(A)

Liicdau,i

•

Z L + u^

Thay U Q ^ I Q Z L

= 1-

(F)

Vi mach chi c6 C thi i som pha hon u la n/2 nen
1207rt-^ + ^
120Trt + • Chon A .
i = I>/2cos 1207tt-4 + -2 =4cos

:fUSU.:dt'

Up

u = -0,5uc + U c = 0,5uc = 50 cos 1007Ct + - (V)=>ChonD. j j i ,:v

6,
Chu y:
(dm)
in:t)\i ^n;.iC) .!'-<i,:,) en npiu u\p iBsi oi\'> UM
1) NcU cho •

7,271

Uc

Dien ap giij'a hai dau doan mach: u = U L +

C. Dong dien tuc thai qua tu dien la i = 4cos(1007it + 7i/4) ( A ) .

1

V01

507Ct 571

dong dien trong mach la
A . i = 4 >/2 cos(1007rt + 7r/6) ( A ) .

B. i = 5cos(1007rt + 7t/6) ( A ) .

C. i = 5cos(1007tt - 7r/6) ( A ) .

D. i = 4 V2 cos(1007rt - 7t/6) ( A ) .

h/.'AM.ii'^y'AH

Cdch 1: Gidi tuan tu:
1
1

Huongdan

);|^:Kr;i;flj!p*iJ,r.):^i;^»;.fi!a

iriJ'rrs! hamh. it'jil: ••.!,!'•

: ::

,.


Bo

trfl

kicn

Ihitc

V^t li LTDH

tren

hcnii

VTV2,

\

/

=> C O S l O O T l t -

u = I Q Z C COS l O O T l t - -

3/

\

1 =

u

3
2

+

sin l O O T T t V

2J

2

-1

2
[1,50

Cdch 2: Gidi nhanh (van

J

Cty

Bicn

3.

IQZC

u = I Q Z , ^ cos

-i
3y

u,

^5.10

+

^2

150

Thny U() = l o Z c

-4

.I„=5(A)

In .50

chieu. Biet dien ap c6 gia t r i tiic t h o i 60^6

lOOKt--

= -+k.27T
4

lOOTit--

=

= 600V2cos[ l O O T i t - - | ( V ) .
V
6 j

+ 1.271

(V) t h i d o n g dien c6 gia

t r i tuc t h o i -^6 ( A ) . Ban dau d o n g dien tuc thoi bang gia t r i cue dai, bieu
thii'c C L i a d o n g dien la

+ A ( s ) ( k = 0/1,2..)

1
240

50

1

t = --

(V) t h i d o n g dien c6 gia t r i tuc

1200

3) Ta thay:

^/2

4

6,

t h o i yfl (A) va k h i dien ap c6 gia t r i tuc t h a i SOs/l

2014

+ — ( s ) ( l = 1,2,3..)
50

= 1006 d u 2 => t = 1006T + 1 , .

De t i n h t2 ta c6 the d u n g v o n g tron l u g n g giac:

A. i = 2^y3cos(^007tt + 7t/2) ( A ) .

B. i = 2 V2 coslOOTtt ( A ) .

C. i = 2 V 2 c o s 5 0 7 i t ( A ) .

D . i = 2 ^/3 cos(507it + 7r/2)(A).
Huong

360.6

360.2

10071

CO

1

Up

coC

I„

rad

• CO = 50TC

200

(s)

t = 1006.0,02 + — = 20,135 (s)
200
'
^>

,

,

2K + 2 7 1 -

(t>, - On

,

dan

Uo=120V2

4

Vift

_3^ = 6 0 0 V 2 c o s f l 0 0 7 t . 5 . 1 0 ' ' " ^ - - l = 3 0 0 V 6 ( V ) .
•I
6y

6

i = 5cos 100Ttt + - ( A ) : ^ C h o n B.
6
V i d u 10: Dat vao hai dau tu dien c6 dien d u n g 1/{3n) (mF) m o t dien ap xoay

6

2

2) Giai p h u o n g t r i n h : u = 600 (V) => cos l O O T t t - -

= 1-

Kliang

MTV DVVH

=> In = 5 A => i = 5cos 1007:t + -

V i mcich chi c6 C thi i som pha hem u la TI/2 nen

2

3

tat):

D u a vao he thuc: -4r +

Tnnn

V i mach chi c6 tu dien nen dien ap tre pha hon d o n g dien la n/l:

u

(

\

i = IQ cos

t^p 2 - Chu Vdn

4) Ta thay:

2014

= 503 du: 2 => t = 503T + t j .

De t i n h t2 ta c6 the d u n g v o n g t r o n l u o n g giac:
V i ban dau d o n g dien tiic t h o i bang gia trj eye dai, bieu thiic ciia d o n g d i e n
CO

dang i = I,, cos cot thay so vao ta d u g c i = 2V2 COSSOTTI ( A ) => Clion C.

V i d u 11: Dat vao hai ban tu dien c6 dien d u n g 100/(37r) (|aF) m o t dien ap xoay

27t

O , - On
t , _= ^2
CO

1

lOOTt

1
(s) = > t = 503.0,02 +
120' '
•
120

chieu u = Uiicos(1007it + (pu) (V) t h i d o n g dien qua t u c6 bieu thuc

CM

i = 2 V 2 cos{1007tt + 7x/3) ( A ) .

loan cho dien ap (dong dien) a thai diem nay tim dong dim

1) T i n h d i e n ap g i i i a hai ban t u tai t h o i d i e m t = 5 (ms).
2) Xac d i n h cac t h a i d i e m de dien ap u = 600 (V).

»

3) Xac d j n h t h o i d i e m Ian t h u 2014 de u = -300 V2 (V).
4) Xac d j n h t h o i d i e m ian t h u 2014 de |u| = 300 V2
Huang
1) T i n h d u n g Ichang: Z c = — = 3 0 0 ( Q ) .
coC

dan

(V).

t•

6041
600

y: Vi v6i mach chi chiia L hoqc C thi u va i vuong pha nhau nen thuang c6 bai
(dien dp) a thai diem

triivc do hoqc sail do mot khoang thai gian (vuong pha) A t = (2n + l)T/4:
U2

I ',/

V i d\ 12: D a t vao hai dau doan mach chi c6 cuon cam t h u a n c6 d o t u cam
0,4/7t (H) m o t dien ap xoay chieu u = UocoslOOTct (V). N e u tai t h a i d i e m ti dien
ap la 60 (V) t h i c u o n g do dong dien tai t h o i d i e m ti + 0,035 (s) c6 do Ion la
A. 1,5 A .

B. 1,25 A .

C. 1,5 V3 A .

D. 2

V2

A.


Cty

B S tr^ kieti thUc V^t II LTDlt tteti k&nh VTV2. t$p 2 - Chu VSn Bi&n

Huong

71
=0,035 = —

Cam khang Z, = w L = 4 0 ( Q ) . V i t2
60

pha nen:

40

dan

= l , 5 ( A ) = > C h o n A.

V i du 1: Dat dien ap xoay chieu c6 trj hieu d u n g 120
la hai thoi d i e m v u o n g

m o t dien ap xoay chieu u = UocoslOOnt (V). N e u tai t h a i d i e m ti dien ap la
50 (V) t h i c u o n g do d o n g dien tai thai d i e m ti + 0,005 (s) la:
B. 0 , 5 A .

C. 1,5 A .
Huong

z,

1

=•

(oC

=

.

. i

'(t]+0,005)

1007rt +

-

2.

COS

•(ti+0,005) -

D . 0,8 (s).

T h o i gian hoat d o n g trong 1 s:

1

b

1
arccos

12071

U,)

2/;^"^t!::'''';:''^^'^'''^^

60V2

= 60.4.

Bie't den sang k h i dien ap

=50

A. 0,5 Ian.

1007i(ti+0,005)-

°

100

7= = —(s) => Lnon

120V2

L.

3 ''

dat vao den khong nho h o n 155 V. Ty so giCra

filsJ

, (|„.,

,>|' ,|

^0

'

T h a i gian hoat d o n g t r o n g m o t chu k i : t^ = 41, = 4.—arccos—

thai CO gia tri bang 0,5Io vao n h u n g thai diem

j.

B. 1/400 s v a 2/400 s.
dan

K h i bai toan chi yeu cau t i m hai thai diem dau c6 the giai p h u a n g trinh
sin (cot + cp) = s i n a =

Un

l u o n g giac:

arccosi

•

D . 1/600 va 5/600 s.

I
Huang

1
b
. T h a i gian hoat dong trong t s: thj = t.f.4.—arccos—

(s)

;'

losinlOOTit. T r o n g khoang thai gian tCf 0 den 0,01 ? c u o n g do d o n g dien tiic

.

t

'

d i j n g v o n g t r o n l u o n g giac.

A. 1/300 s v a 2/300 s..-?.
C. 1/500 s va 3/500 s.

''''"^

U(,

~

• ,:,

De xac d i n h cac thoi diem c6 the d u n g giai p h u o n g t r i n h l u o n g giac hoac

Thoi gian hoat dong trong 1 s: ft^ = f.4.—arccos —

1

v

V i du 1: (DH-2007) D o n g dien chay qua m o t doan mach c6 bieu thuc i =

1
b
T h a i gian hoat d o n g t r o n g m o t nua chu k i : 2t, = 2. —arccos-—-

—T

2T

2) T h a i diem de dong dien hoac dien ap nhan mot gia tri nhat dinh

chi hoat d o n g k h i u nam ngoai khoang (-b, b) (xem h i n h ve)

CO

D . 3 Ian.

tt

chi hoat d o n g k h i dien ap tuc thai c6 gia t r i k h o n g nho h o n b. Vay thiet bj

CO

Ian.

dan

T

tT h o i gian den tat trong m o t chu k i : t, = T - tj^ = — => — = 2 => Chgn B.

rfniiiaO,

M o t thiet bj d i e n duoc dat d u a i dien ap xoay chieu u = Uocoscot (V). Thiet b i

"

C. ^

T h o i gian den sang trong m o t chu k i :
.
. ^
b
T
155
t, = 4.—arccos
= 4.—arccosCO
2n
220V2

r' i;*, ' ' * •
p ,

B. 2 Ian.
Huang

lift:

^- = - 0 , 5 ( A ) =>Chon A .

1) T h a i gian thiet b i hoat dong.

,.

•

dan

khoang thai gian den sang va khoang thoi gian den tat t r o n g m o t chu ky la

Phuangphdpgidi

HtU „

V tan so'60 H z vao hai

V i du 2: Mc)t den o n g su d u n g dien ap xoay chieu c6 gia trj hieu d u n g 220V.

BAITOAN LIEN QUAN DEN THOfI GIAN;0

r

C.2/3(s).
Huong

CO

dan

;„•••

,

B. l/3(s).

t = f.4. —arccos

D.-1,5A.

= 1 0 0 Q ; u = Uo cosl00Tit=i> U(f^j = U , , coslOOTtti

cos

Vlft

dau m o t bong den h u y n h quang. Bie't den chi sang len k h i dien ap dat vao
A. l/2(s).

V i du 13: Dat vao hai dau doan mach chi c6 tu dien c6 dien d u n g 0,l/7i (mF)

A.-0,5 A.

M I V U VVH Khang

den k h o n g nho h o n 60 N/2 V. T h o i gian den sang trong m o i giay la:

.-./c',,;

r-iT-

Train

T

arcsin^

'
arcsin^

!

'—*
arccosS-

cos(o)t + cp) = c c « a :
j

cot + cp = a +

(271)

o,t + (p = 7 r - a + (27i)

^P^^fk^''^--

cot + (p = a + (2?:)

„: .,

ojt+ 9 = - a +

(27t)

(Neu t i m ra t < 0 m o i cong 2 ? : ) .
O

1
b
— arccos —

1
b
—arccos —

i = Iosinl007it =

^

1
(s)
600
=> Chon D.
5
-(s)
^J^''
1007tt = — = > t =
600
1007rt = - :
6

t =

13


B6

trff kiSn

thCrc

V^t l i L T B t l trSn

kSnh

VTV2.

t^p

2

- Chu VSn

Cty

Bien

Timti nrv

DVVH

Khang

Vipt

V i du 2: D i e n ap hai dau doan mach c6 bieu thiVc u = 200cos(1 OOTit + 57r/6)

V i du 4: D i e n ap giua hai dau m o t doan mach ccS bieu thuc u = U()COS(2TTt/T).

(u do bang v o n , t d o bang giay). T r o n g i
T i n h t u t h a i d i e m t = 0 s, thi thoi d i e m lan t h u 2014 ma u = 0,5Uo va dang

ap tiVc thoi CO gia trj bang 100 V vao n h u n g t h o i d i e m
A. 3/200 s va 5/600 s.
'

tang la

v

' ' '

1007rt + — = - = ^ t
6
3
1 OOTTt + — =
6

3

Lan
A
'

= - —(s)<0
200

tl

=--^

dao

271-0

+

,

, ;

_5T

271

0)

T'

Lan

2: t 2 = t, + T , . . .

Lan

2014: 12014 = t i +2013T
5T

2014

1 dien ap tuc thoi c6 gia trj bang
pha

3

cl>i - O

=•

^ t= -—(s) <0
600

Vj tri xuat phat u n g v o l pha dao dong: 0 „ = —
6
voi

D . 12083.T/6.

1 ma u = 0,5U(i va dang tang u n g v o i pha dao d o n g :

O j = - ^ + 271 nen t h a i gian:

Cdch 2: Dung vdng iron luang gidc

ung

C. 12059.T/6.

Vi t r i xuat phat u n g v o i pha dao d o n g : O,, = 0

1007rt + — = - + 2 T : ^ t = — ( s )
6
3
200

57:

''

nua d u o i v o n g tron k r o n g giac (moi chu k i chi c6 m o t lan).

=> Chon A. (Neu k h o n g cong them 2n

V

r

Cac t h a i d i e m ma u = 0,5Uo va dang tang t h i chuyen d o n g t r o n deu nam o

1007rt + — = - - + 27i=>t = — ( s )
6
3
600^ ^

100

. ]

B. 12055.T/6.

Huotig dan

Cdch 1: Gidi phumig trinh luong gidc

Lan

,-\y-''''

D . 1/200 va 7/600 s.
Huong dan

u = 100=^ cos lOOTTt

'•

A. 12089.T/6.

B. 1/400 s va 2/400 s.

\f|s^,,i;,:,

C. 1/500 s v a 3/500 s.

, i

6

12083T

+ 20131 =

• ChonU.

6

V i du 5: D i e n ap giua hai dau m o t doan mach c6 bieu thuc u = Uocos(2Tit/T).

dong:

Ti'nh t u t h o i d i e m t = 0 s, t h i thoi d i e m lan t h u 2010 ma u = 0,5U() va dang

+ 2Tt nen thoi gian:

giam la
71
„
5T:
- - + 271 - - -

0)
Lan

3

10071

6

A.6031.T/6.
600

V i t r i xuat phat: 0 „

2 dien ap tuc thoi c6 gia t r i bang 100 V u n g v o l pha dao d o n g :
71

57r

Lan

3^^^"T
<I>2 = — + 27T nen thoi gian: t 2 = ^ 2 - O o
w
10071
200
3
V i du 3: D i e n ap giCra hai dau m o t doan mach c6 bieu thuc: u = 120sin]007rt
TT

Lan
2010

(u do bang v o n , t do bang giay). H a y xnc d j n h cac thai d i e m ma dien ap
A. t = J/3 + k ( m s ) .

B. t = l/6 + k ( m s ) .

C. t = l/3 + 20k (ms).

D. t = 5/3 + 20k (ms).

'* Hicangdan
.
,
u = 120sinl007tt = 60
71 . .
' ' hihm^:r>:
,
i n n . „ => 1 OOTlt = — + k27t
u = 1007i.l20cosl007rt>0
6
1
2
1
, 2 ^
-+k
.10' (ms) = - + 2 0 . k ( m s ) => C h o n D .
=>t =
+k

(s) =
1600
100 J
3
600
100

C. 12059.T/6.

'<

dan

Huang

= ( IOOTT.O) =

0

D . 6025.T/6.

'" " '

T
1 ma u = 0,5Uo theo chieu am: t, = — .
6
2010 ma u = 0,5Uu theo chieu am:

T/6

^'tW)-'

6

=>ChonB.

u = 60 V va d a n g tang ( v o i k = 0,1, 2,...).

B.12055.T/6.

• ,

,

,

,^

V i du 6: Dat vao hai dau doan mach m o t dien ap u = UocoslOOrct (V). T r o n g
chu k i t h u 3 cua d o n g dien, cac thoi d i e m dien ap tuc t h o i u c6 gia t r i bang
dien ap hieu d u n g la

A. 0,0625 s va 0,0675 s. V
C.0,0025 s va 0,0075 s.
%

•I

' ••/

j. '
•"'

B. 0,0225 s va a0275 s.
D . 0,0425 s va 0,0575 s.

Huang dan

Cdch 1: Gidi phuang trinh luong gidc.

'

;


Bidttff

USn

thiic

V^t It LTDH trSn kenh

VTV2.

t4p 2 - Chu

Van

Cty Timii

Blgn

Chu y: Trong mot chu ki c6 4 tliai diem de /u / =b<
= j = i > t i =0,0025(s)
C h u k i t h u 1: u =

n md lul

•COSl007tt = -

= - j + 27r=>t2 = a 0 ] 7 5 ( s )
Chu k i thu- 2: {
It^ = t 2 + T = 0,0375(s)

Chu k i t h u 3:

:.f 1, ' 'J

'-^->

[ t , = t 2 + 2 T = 0,0575 (s)

n
ti =
^

7t „
O, = — + 2;:

2 den

Id :

Lan

3 den u-i Id :

Lan

4 den

Id :

0)

=> to

=

_^

= 0,0225(s)
'?r.'

:.}:£rifiJ

i ''

^^"'^

vd

den

Id:

Lan

4n

+ 2 den

Lan

4n

+ 3 den

la

Lan

4n

+ 4 den

la

= nT

t4„+]

t i u ^ i = t i + nT.

,
, So l a n
f neu dU 1 => t = nT + t,
nhanh:
•
= n<^
,

+

tj

W j la : i^^x+Z = nT + t 2

.
: t 4 , - , + 3 = nT

+13

t4.

Solan
4

: t 4 n + 4 = nT

= n<;

+

=> t

t4

= nT +

tj

neu dif 2 = >

t

= nT +

t2

neu d u 3 = >

t

= nT +

t3

=> t

:2

A,

= n T +14

Ta

co

the

,.,

[ n e u d U 2 = > t = nT + t2

Huong
Ta nhan tha'y:

rut

ra

'meo'

-'iiu/

••) f:V

dan

•'

2013
= 503 d u 1 ^

t2oi3

= 503T +

tj.

Ta d i i n g v o n g t r o n l u g n g giac de t i n h t i :
\'

T

Idm

24

, „

,

'

^hmr

(A) £ , v

D. t = 12073/1200 (s).

C . t = 2411/240 (s).

-

gt)

B. t = 9649/1200 (s).

K:V-M

•

Do do, trong chu ki dau tien c6 hai thai diem ti vn ti; chu ki thu 2 c6 hai tlwi diem
= t i + nT

+1

dp d o n g d i e n tuc t h a i bang c u a n g do d o n g d i e n hi^u d u n g la

diem tren true ung vai hai diem tren vdng trdn lugng gidc (trit hai vi tri Men).

t2i,vi

4n

A . t = 12043/12000 (s). (A)

Chii y: Ncu khong han chcboi dieu kien dang tang hoac dang gidm thi ung v&i mot

t4 = t i + T;...

thai diem lan thie

- n/3) (A) (t do b a n g giay). T h a i d i e m t h u 2013 gia t r i t u y ? t d o i ciia c u o n g

+271-0
IOOTI

VJ^

V i du 8: D o n g d i e n xoay chieu qua m o t doan mach co b i e u t h i i c i = Iocos(1007it

IOOTI

Oj-Og

Lan

neu dif 4

= 0,0025(s)

t5 = t i + 2 T = 0,0425(s)
Chu k i thiV 3:
^ ^ => Chon D.
tg = t 2 + 2 T = 0,0575 (s)

•

2

Lan

Kbang

loo':.

{

-0

(0

f.3 = t i + T vd

ld:ti.

,
,
Ta CO the rut ra meo lam nhanh:

' 1

• I

2:

Lanldenu^

neu dif 1

V i t r i xua't phat: 0 ^ = 0

Lan

;TV„.if.;

Uo. Detim

ta can luu y:

'tg = t i + 2 T = 0,0425(s)

Cdch 2: Diing vdng iron luong gidc.

Lan 1: O, = '
4

1) i ' . f ; i

=h

PTTV DVVn

iTlW

12013

= 503T + 24

12073T

12073

24

1200

(s) ^ Chon D.

- ' ^ ) = - * 3

V i d u 7: D o n g d i e n xoay chieu qua m o t doan mach co bieu t h u c i = Iocos(1007rt
- n/3) (A) (t do bang giay). T h o i diem t h u 2009 c u o n g do d o n g dien tuc thai

N e u biet gia t r i tuc t h a i 6 t h a i d i e m nay t i m gia t r j a t h a i d i e m khac ta co

i = Io/V2 la
A. t = 12049/1440 (s).

; ; , .1

C . t = 24113/1440 (s).

Ta tha'y:

B. t = 24097/14400 (s).
D . t = 22049/1440(8).

Huang
2009

3) Cac gia tri tuc thoi 6 cac thoi diem

dan

= 1004 dU 1 ^ t2oo9 - 1004T + t^,

Ta d u n g v o n g tron l u a n g giac de t i n h t i :

T

the giai p h u a n g t r i n h l u g n g giac hoac d i m g v o n g t r o n l u g n g giac.
V i du 1: (DH-2010) Tai t h a i d i e m t, d i e n ap u = 200 ^ 2 cos{1007tt - n/2) (trong
do u t i n h bang V, t t i n h bang s) co gia t r i 100 V 2 (V) va d a n g g i a m . Sau t h a i

A. -100 V.

U(t^) =200V2cos

> «,':-»U,l/:i.J'

T
24097
t2oo9 = 1004T + — = ^ ~ - ( s ) ^

Chon B.

Cdch 1:
U(,l

IK

B. 100 V3 (V).
Huang

t
^ 2 4

j

d i e m do 1/300 (s), d i e n ap nay co gia trj la

= -200o)sin

OOti

^

—

2

C. -100 ^ 2 (V).

'f

j

f

D . 200 V. ST

dan

= IOOV2.
COti —
^

2

7t

7t
^
= — => coti =
3

^

5n

—

6

cot
17


Cty mHHnTVDVVHlihang

B6 trjf kie'n thiic V^t li LTBH tren kcnh VTV2. t^p 2 - Chu VSn Bien

ti +

= 200V2cos
300 j

1 '

71

300>

2_

^

CO t1 +

V ^

—

= -100^/2(V)=>ChonC.

Cdch 2: K h i i = N/2 (A) va dang giam t h i pha dao d o n g c6 the chon: O j = —,
3

Cdchl:
K h i u = 100 V2 (V) va dang giam t h i pha dao d o n g c6 the chon:

=- .

Sau t h a i d i e m do 1/300 (s) (tuang u n g v a i goc quet Acj) = (oAt = 1007t/300 = 7t/3)
t h i pha dao d o n g : O2 =

+ AO = —

f

=>U2 =200V2cosO2 =-100>/2(V)=>ChonC.

thoi d i e m gan nhat de i = ^/6 (A) t h i pha dao d o n g O2 = - — + 2T[ .
6

0 0'

D o do, t h o i gian: t i = —

B. 271/3.

' •

A . 2 (A) hoac - 2 ( A ) .

B. - V2 (A) hoac 2 ( A ) .

C. ->/3 (A) hoac 2 (A).

D . Vs (A) hoac - 2 ( A ) .
dan

V i k h o n g Hen q u a n den chieu dang tang hoac dang g i a m nen ta c6 the giai
p h u o n g t r i n h l u g n g giac de t i m nhanh ket qua.

i = 4cosl207i t i +•
240

1207iti = ± ^

2J

6

2.

= ±2(A)

i = 2 V2 cos(1007it + (p) (A), t t i n h bang giay (s). Vao m o t t h a i d i e m nao do,
B. 5/600 (s).
Huang
Cdchl:
t =

C. 2/300 (s).
dan

•'^•i^f>fi-"

3
T. T T
3T
(s)=^Chon A.
+ — + — + — =:
=
12
4
4
6
4
200
T

__l—^
-A

\2 = IQ cos (cot +

0

0,5A

0,5AV3

2

^/3Io
2 =>(cot + cp2) = -

92) = -

6

'

D u a vao v o n g l u g n g giac, hai d o n g dien xoay chieu c6 cung t r i tuc thai
0,5 ^/3 lo, d o n g d i e n dang g i a m iVng v o l niia tren con d o n g dien dang tang
l i n g v o i nua d u o i . H a i d o n g dien nay lech pha nhau la Acp = —
•, '
...
.3

d a n g g i a m t h i sau do it nhat la bao lau t h i i = + V6 A?

A . 3/200 (s).

LA1

i ' l = - W I Q sin(cot + (pi) > 0

Cdchl:

V i d\ 3: D o n g dien xoay chieu chay qua m g t doan m a c h c6 bieu thiic
1= sfl Ava

i,=IoCos(cot.cpO = - ^ ^ ^ ^ ^ ^ ^ ^ ^ _ .

^ Acp = - => Chon A.

4 COS 1207rti + - = 4 COS

V,;,

i '2 = -COIQ sin (cot + (p2 ) < 0

C u a n g do d o n g d i e n a t h o i d i e m t = ti + 1/240 (s):
1

dan

:"'=,'"v;:r

Cdchl:

Z

D.7C/2.

C. 7t.

Huong

Tai t h o i d i e m ti nao do, d o n g dien c6 c u a n g

= 4cosl207tti = 2V3

•

3

=—
^ =
(s) => Chon A
' '
0)
lOOTt
200^
V i du 4: Vao cung mot thoi diem nao do hai dong dien xoay chieu h = Iocos(cot + cpi

A . 7t/3.

bieu thiic i = 4cos(1207it) (A), t do bang giay.

Huong

- ^ + 2TC-~
A
q

tang con m o t d o n g dien dang giam. H a i d o n g dien nay lech pha n h a u

V i du 2: D o n g d i e n chay qua m o t doan mach c6

c u a n g do d o n g dien bang J-

-

va i2= Incos(cot + 92) CO ciing trj tuc thai 0,5^/3 lo, n h u n g m o t d o n g dien dang

,,, .

do 2V3 A . D e h t h a i d i e m t = ti + 1/240 (s),

Vl^,

B A I T O A N L I E N QUAN DEN D l | N

D . 1/100 (s).

Chon A .

LlT^NG

Phuong phdp giai

1) Dien lugng chuyen qua tiet dien thang day dan
Theo d i n h nghia:
i =

^
dt

dq = i d t .

D i e n l u g n g chuyen qua tiet dien thang ciia day dan t i n h t u t h a i d i e m ti den


B6 tr^ ki&'n thiic

V$t li LTOH

VTV2, t$p 2 — Chu VSn

Iren kenh

ciyfimnnrv

BlSn

D

vvn Khang vl^t

1 / 300
Inr

i = Io sin(cDt + (p)=>Q = - —cos(cDt + {p)

COs(cot2 + ( p ) - C O s ( 0 3 t j +cp)

dt

2cos

Qi =

(0

« 5,513.10"-* ( C )

"

i

1

Inr

i = IQ c o s ( « ) t 4- (p) => Q = — s i n ( ( B t + cp)

= —rsin(cot2 +(p)-sin(ff)ti +(p)
tt)

CO

1/300

^

2sin(1007rt)dt

Q2 =

vJ().»V

V i du 1: D o n g dien xoay chieu chay trong day dan c6 bieu i = 2cos(100Kt - 7t/6)
« 3,183.10"^ ( C )

(A) (t do bang giay). T i n h d i ^ n l u o n g chuyen qua tiet d i ^ n thang ciia day
d a n t r o n g l / 3 0 0 { s ) k e til-liic t = 0.
A . 6,666 m C .

=> Chon A.

•^•• >

B. 5,513 m C .

C. 6,366 m C .

D . 6,092 m C .

Huang dan

,."\)t . A ' '

Cdchl:
1/300

1/300

t2

Q = Jidt =

2cos ^ O O T t t - - ^ dt = -sin l O O T C t - IOOTT
3
0

=> Chon C.

V i du 3: D o n g d i e n xoay chieu chay trong day d a n c6 tan so goc co. D i e n l u g n g
chuyen qua tiet d i § n thang cua day dan t r o n g 1/6 chu k i d o n g dien ke t u liic
d o n g dien bang k h o n g la Q i . C u o n g do d o n g d i e n cue d a i la

T/6

• | n K : /i-

I„

.;
O

t (S)

Cdch 2: Viet lai bieu thuc dong dien duai

ft' • At

'J--..-' -i

;

/yii,
nT/6

271
[ ]osincotdt = — - c o s — t
T Jo

In

> Ig = 2coQ, => Chon B.

2ci)

Chu y:

2) Khodng thai gian hai Idn lien tiep dong dien triet tieu Id T/2 nen dien lugng chuyen
,.

dang i = IQ sin cot vd tinh tich phan

u',1,

1) Dong dien den chieu luc no triet tieu i = 0.

Cdch 1: Gidi phuang trinh i = 0 detim ra ti

'1

J

'V

,

• = i = 1(, sincot => dc] = I,) sincot.dt

•Q, =

•,

D . 0,5.Qico.

Huong dan
dt

Chu y: De tinh dien lugng chuyen qua tiet dien thang cua day dan trong thai gian

idt

C. Qico.
.^-lUih

tren m a y t i n h de t i n h tich phan.

sau do tinh tich phan: Q=

B. 2Q1C0.

A . 6Q1C0.

Cdch 2: D i i n g m a y t i n h casio Fx 570ES, chon d o n v j goc la rad va b a m p h i m I

tl+At

;

> 6,366.10"^ ( C )

: j i .ji

At ketit luc dong dien bang 0, ta c6 the lam theo hai each:

'

-i^

qua tiet dien thang cua day dan trong thai gian do la:
T/2
T/2 2I0
IQ sin cotdt = — ( 1 - cos cot)
•iT/2
0
CO
CO
Den mm chu ki tiep theo cUng co —

f

,. ; j 0 / i ' . , 1 :A *;

dien liiyng chuyen ve nen dien lugng

(0

J

Q = Jl(,sincotdt = —(1-coscoAt) (tich phan nay chinh Id dien tich phan to mdu
CO

chuyen qua tiet dien thdng cua day dan trong mot chu ki la bang 0 nhung do Idn
4Ir

dien lugng chuyen dichuyen vela |Q|^ = — - .

tren do thi).

(0

vi du 2: M a c day d a n vao n g u o n xoay chieu o n d j n h t h i d o n g d i e n chay qua c6
b i e u thiic i = 2cos(1007it - n/3) ( A ) . D i f n l u g n g c h u y e n qua tiet d i e n thang

0

\

Do Idn dien lugng chuyen qua tiet dien thang cm day dan sau Is vd sau thai gian t
lanlugtld

]^\Q\j

vd

^\Q\^.

cua day d a n t r o n g t h o i gian 1/300 s ke t u liic t = 0 va ke tie liic i = 0 Ian
lucrt la

V i du 4: Cho d o n g dien xoay chieu i = 27csin(1007tt) ( A ) (t do bang giay) qua

,

A . 5,513 m C va 3,183 m C .
^ C. 8,183 m C v a 5,513 m C .

B. 3,858 m C va 5,513 m C .

mach. T i n h d o I o n dien l u g n g qua mach trong thoi gian 5 p h i i t .

D . 87 m C va 3,183 m C .

A . 600'C.

'2

dt

jidt
'1

C. 1800C.

D . 2400 C.

Huong dan

Huang dan
• dq =i d t = > Q =

B. 1200 c .

|Q| = 1|Q|
T

= t — ^ = 5 . 6 0 . — = 1200(C) ^ Chon B.
271 CO
27t
21


Bd trg kie'n

thitc

V^t It LTDH

tr^n kSnh

t^p 2 - Cha Van

VTV2.

Cty Timn nrv

2) T h e tich k h i thoat ra k h i dien phan dung dich axit H2SO4
+ The tich k h i H 2 va O 2 0 D K T C thoat ra 6 m o i di§n cue trong n u a c h u k i Ian
lugtla:

Vlft

BAI TOAN LIEN QUAN DEN MACH RLC NOI TIEP

+ D i e n l u o n g qua tiet dien thang cua day d a n trong 1/2 c h u k y : Q1/2 = 2Io/co.

Q

P VVH Khang

Blin

phtiong phdp

gidi

1) Tong tro, dp l?ch pha, gia tri hi#u dung

1/2

= ; ^ n , 2 ( l ) va
=-^5,6(1).
96500 ' ^ '

'
96500
+ The tich k h i H 2 va O 2 6 D K T C thoat ra 6 m o i dien cue t r o n g t h o i gian t Ian
va
•— V T .
.
= ^ ^V 1r v
a V f ^ . ==^^2T
+ T o n g the tich k h i H 2 va O 2 6 D K T C thoat ra 0 m o i dien cue t r o n g t h o i gian t

Tong t r o

Z = VR'+(ZL-ZC)'

luotla:

t

tan(p =

IT", if

Z| - Z c _ U L - U

D o lech pha:

R

.,AiX..r

la: V = V H 2 + V O 2 = - ( V , + V 2 ) .

V i du 5: Cho d o n g dien xoay chieu i = 7:sin(1007it) ( A ) (t do bang giay) chay qua
b i n h dien phan chiia d u n g djch

H2SO4

(p > 0 : u sdm

v o i cac dien cue tro. T i n h the tich k h i

phahdn i

m a c h c6 t i n h c a m k h a n g

H 2 6 dieu kien tieu chuan thoat ra trong thoi gian 16 p h i i t 5 giay 6 m o i dien

9 < 0 : u t r e p h a h d n i => m a c h c6 t i n h d u n g

cue.

(p = 0 : u , i C l i n g p h a .

A. 0,168 lit.

; \,:

B. 0,224 lit.

C. 0,112 lit.

D . 0,056 l i t .

Huong ^an
Q i / 2 = 2 ^ = 2 - ^ = 0,02(C)
ft)

^

t Qi/2 . n , 2 = ^ : ^ l l , 2
T 96500""
0,02 96500

"2

•

IOOT:

phan chua d u n g djch H2SO4 v o i cac dien cue t r o . T i n h the tich k h i 0 dieu
kien tieu chuan thoat ra trong thoi gian 16 p h u t 6 m o i dien cue.
B. 0,0235 lit.
'

C. 0,047 lit.

.
,
U
UR

UL UC
C u o n g d o hieu d u n g I = — = — = — - =
= —Z
R
ZL
Z ( - Zj^^
^

Dien ap tren doan mach U ^ N = 12^^

=^ZMN

D . 0,056 l i t .

Huong dan

r = 40(Q) CO d o t u cam L = 0,4/7i(H) va tu dien c6 dien d u n g C = l/(147t)(mF).
Mac mach vao n g u o n dien xoay chieu tan so goc IOOTT (rad/s). T o n g t r o ciia
mach dien la
A. 150 Q.

B. 125 Q.

C. 100 V2 Q.

(oC

=

V H 2 + V O 2 = Y

300

0,018

0,02 96500

^'/^-.ll,2 + - ^ . 5 , 6
96500
96500

.11,2 +

0,018
96500

.5,6 = 0,047{\)=>ChgnC.

[

D . 140

; >= S j

Huong dan

Z L = w L = 10071.— = 4 0 ( Q ) ; Z c = ^

V

„
-ml nid iob gnoriW

V i d u 1: Mach dien n o i tiep g o m dien tro R = 60 (Q), cuon day c6 dien t r o thuan

= 0,112(l)=>C/ip/7C.

V i du 6: C h o d o n g dien xoay chieu c6 gia t r i hieu d u n g 2 A chay qua b i n h dien

A. 0,168 l i t .

khang

IOOTC.

\
10"
147t

= > Z = ^(R + r ) ^ + ( Z L - Z c f = V l 0 0 2 + ( 4 0 - 1 4 0 f = 1 0 0 ^ 2 ( Q ) '
'i)i'> nan , •
=> Chon D .
du 2: D a t m o t di$n ap xoay chieu vao hai d a u m o t doan mach mac n o i tiep
g o m t u dien c6 d u n g khang 2 0 0 Q , dien t r o thuan 3 0 N / 3 Q va cuon cam c6
dien t r o 5 0 ^f3 Q CO cam khang 2 8 0 Q . Dien ap giua hai d a u doan mach
A. s o m pha h o n c u o n g d o d o n g dien la n/4.
B. s d m pha h o n c u o n g d o d o n g dien la Ti/6.
C. tre pha h o n c u o n g d o d o n g dien la n/4.
D. tre pha h o n c u o n g d o d o n g dien la 71/6.

j ,
• >
23


B 6 tr^ hien thiic

V^t li LTBH

trSn kenh

VTV2. t^p 2 - Chu Van Bl&n

Huong dan
_ Z L - Zc _ 280 - 200 _ 1
.{p = ^ > 0
^"^^
R + r ~30>/3 + 50>/3 ~ Vs
=> Dien ap sam pha hon dong dien => Chon B
Vi du 3: Mot mach dien mac noi tiep theo dung thu t u gom dien tro thuan
R = 30 Q, tu dien 1 c6 dien dung
= 1/(3TC) (mF) va tu dien 2 c6 dien dung

Vi du 6: Cho mach dien xoay chieu RLC mac no'i tiep theo dung thii tu gom
cuon thuan cam c6 cam khang 14 (Q), dien tro thuan 8 Q, tu dien c6 dung
khang 6 (Q), biet dien ap gifra hai dau mach c6 gia tri hieu dung la 200 (V).
Dien ap hieu dung tren doan RC la
A.250(V).

C2 = I/TT (mF). Dien ap giiia hai dau doan mach la u = 100N/2 coslOOTit ( V ) ,

Cuang do hieu dung trong mach la - ' ' . rir:..._il,':i
A. 1,00 A.

B. 0,25 A.
.

Zo=-

C. 2 A.

lOOn.

D. 0,50 A.

Huang dan
^

coC

7^ = 10(Q)

Vi du 4: (DH-20n) Dat mot dien ap xoay chieu c6 gia trj hieu dung va tan so

URC

= IZRC = ^ Z R C =

khong doi Ian krot vao hai dau dien tro thuan R, cuon cam thuan c6 do tu

A. 71/4.

tan (PKL = ^

C. 0,15 A.

0,25

0,5

=

U

V0,25^

• = 0,2(A)=>Chon A.

.0,5

0,2J

D. 7i/3.
,
,
I Si J

^
f: :

-0

-// V/
' J,.I>I itoiim.nt}ob }om oxt) 'M tp.

= 1 => (pKL = —

-h-nUh i\-i'Q-u{ ml J U J ' J ,;?'J i^:.,
^

•

•
:'m.&)t?i

"'^ (''^''5t'c'L.(i i.dq ^Jit
' ' ^ *^>v OS (b(5i) rxS.O 6j-kj I ' l l

^-

B. 0.
^f-'o o - v -

C. TI/2.

'^'''-V;

y-^

Huangddn

2

•?m Ki>3 mu'j 1/} oQ

tancpcd = - ^ = t a n - = > Z L - V3R

^"

D . - n/3.

0 .g :

JH0v

'
' >K •••

V!-.

(F). Dong dien qua mach c6 bieu thuc la i = 3cos(1007Tt) (A).
i-' •

Dien ap hieu dung giua hai dau doan mach la
A.60V.
1

-

giua hai dau cuon day so voi dien ap giua hai dau doan mach tren la
A. 2n/3.

cuon cam thuan c6 do tu cam L = 0,8/Tr (H) va mot tu dien c6 dien dung

coC

-

^y3 Ian dien ap hieu dung giCra hai dau cuon day. Do lech pha cua dien ap

V i du 5: Cho mot mach dien mac noi tiep gom mot dien tro R = 40(Q),

Zc =

c

dong dien trong mach la 7T/3. Dien ap hieu dung giua hai dau tu dien bang

0,2

U

2.10-V7T

^

Vi du 8: (DH-2008) Cho doan mach dien xoay chieu gom cuon day mac noi tiep

>^+(Z,-Zj^

C =

va u

voi tu dien. Do lech pha ctia dien ap giua hai dau cuon day so voi cuong do

R =— ; Z L = — ; Z c

1=

_„

D. 0,05 A.

Huang dan
U

12572 (V) =^ Chon C . , ,

Z, - Z r
71
Q
--=^=»9LC=-^

, ... vf;
=> 9RL - ^ L C = —

U

=

C. 37r/4.

^

doan mach gom ba phan t u tren mac noi tiep thi cuong do dong dien hieu
dung qua mach la
,

n ,-CI :

r-

^,

, ,

B. 7i/2.

tan (PLC =

B. 0,3A.

+Zr

"''
,
Huang dan
Z, =a)L = 50Q,Zc =
= 100fi
,,
d

(oC
''<•

tuong ung la 0,25A; 0,5A; 0,2A. Neu dat dien ap xoay chieu nay vao hai dau

A. 0,2 A.

\ J . I R ^

di^n tro thuan 50 (Q); cuon day thuan cam c6 do t u cam 0,5/7i (H) va tu di^n

cam L, tu dien co dien dung C thi cuong do dong dien hieu dung qua mach

^,

fir:

CO dien dung 0,1/?! (mF). Tinh do lech pha giira

K

^37t

Z = ^R2 + ( Z c i + Z c 2 f = 50(Q) ^ I = - = — = 2 ( A ) ^ Chon C.

-

-rori

Vi du 7: Cho mach dien xoay chieu tan so 50 (Hz) noi tiep theo dung thu tu:

^ - ^ = 30(Q), Z c 2 = ^

^
(oC

^ U

n,>i •

_

D. 100V2(V).

B. lOO(V).
C. 125V2(V).
Huong dan

B.240V.
1
100..^:!^

C. 150 V . ' ^ f ' " ! '

=^
D.75V2V.

Huang dan
. „

,
0,8
33- = 5 0 ( Q ) ; Z L =roL = 1 0 0 7 : . — = 8 0 ( Q )
71

Zl
tan (p = —^=

o > 2 ^ Z 2 = 2R = ^

Zc = 273R

— Zp

.^.^^

nr
7t
271
„,
.
~ = -^y3=>(p = - - = >ro^.j- 9 = — => Chon A.

,

.^
M

J

Vi du 9: Dat dien ap xoay chieu vao hai dau doan mach AB theo thu tu gom
cuon day thuan cam L c6 cam khang 100 Vs Q, dien tro R = 100 Q va tu dien
C CO dung khang 200^3 Q mac noi tiep, M la diem gii>a L va R, N la diem

Z = ^R^ + ( Z L -Zcf

= 50(Q) => U = I Z = 75V2 (V)

Chon D .

giua ciia R va C. Ket qua nao sau day khong diing?

'

251


Bo trg hiSn thiic

V^t li LTDII

tren kcnh

A . D i e n ap giCra hai dau dpan A N
''

Cty T/VHH nrv D VVH Khang

VTV2, 14p 2 - Cliu Vsin Bien

£

sam pha h a n dien ap giua hai

R

Huong

C

A/

h y ~ j \~^B

Z = JR2+(ZL-ZC)'

Vift

dan
5R
=

dau doan mach A B la 27T/3
UK = I R = — R= ^

B. C u o n g do d o n g dien tie pha 7i/3 so v a i dien ap giua hai dau doan mach A B .

R = 1 2 0 ( V ) ^ C h o n B.

C. D i e n ap giiia hai dau doan A N som pha h o n dien ap g i i i a hai dau doan

mach A B la 2TT/3.
D . D i e n ap giiia hai dau doan mach A B som pha h a n dien ap g i i i a hai dau
tu dien la 7i/6.

.

,,,

Huong
ZL-Zc _

tancpAM = — ^ =
NAN
^
7t

2J

••

[U2^ui + (UL-Uc)'

dan

10073-200V3

IOOV3

ZL

•"

ZL=n,R

U = J u f , + ( U L - U c r Zc = n2R
Chu y: Thay doi link kicn tinh dim dp

n

= > U K = ?

V i du 13: Doan mach xoay chieu noi tiep g o m dien t r a thuan R, tu dien C va
cuon cam thuan L . Dat vao hai dau doan mach m o t d i e n ap xoay chieu on

n

r-

= v3

d j n h t h i dien ap hieu d u n g tren R, L va C Ian l u g t la 6 0 V , 1 2 0 V va 4 0 V .

= > COAM = —
MAN
3

Thay C b o i tu dien C t h i dien ap hieu d u n g tren tu la 1 0 0 V , k h i do, dien ap
hieu d u n g tren R la

= — > 0 : u^B s6m h d n u ^ la — => Chen D .

6
6

A.

''
B. 8 0

150 V .

V.

Goi UR, U L , U C Ian l u g t la dien ap hieu d u n g giiia hai dau dien t r a thuan,
hai dau cuon day va hai dau t u dien. Bie't U K = U L = 0,5Uc thi d o n g d i e n qua

D. 20^/2 V .

C. 40 V .

V i du 10: Cho m o t doan mach R L C k h o n g phan nhanh (cuon day cam thuan).

Huong

dan

UK=60(V)1

Zl =

2R:

UL =120(V) '

mach se:
Uc=40(V)=^U = ^Ui^+(UL-Uc)

A. tre pha 0,257i (rad) so v o i dien ap giiJa hai dau doan mach.
B . tre pha 0,57T (rad) so v o i dien ap hai giua dau doan mach.

=>100^ = U ' K + ( 2 U ' K - 1 0 0 ) ^ ^ U ' K = 8 0 ( V ) = > C h o n B.

D. som pha 0,5n (rad) so v o l dien ap giira hai dau doan mach.

,

tancp =

;

K h i C thay d o i thi U van la 100 V va U ' L = 2 U ' K = > U ^ = U R + ( U ' L - U ' c f

C. som pha 0,25TI (rad) so v o i dien ap giiia hai dau doan mach.
i

Huong dan

=100(V)

,

V i du 14: Doan mach xoay chieu g o m bien t r o R, tu dien C va cuon thuan cam
L mac noi tiep. K h i dieu chinh bien t r o 6 gia trj nao do t h i dien ap hieu

= = ^ ^ ^ ^ - ^ = - 1 = ^ 9 = - - ^ Chen C.

d u n g do d u g c tren bien tra, tu dien va cuon cam Ian l u g t la 50V, 90V va
V i du 11: Dat dien ap 50 V - 50 H z vao doan mach noi tiep g o m dien t r a 40Q
va cuon day thuan cam thi dien ap hieu d u n g giira hai dau cuon cam la
Ui. = 30 V . D o t u cam cua cuon day la
A . 0,4/(71 N / 2 ) ( H ) .

B . 0,3/71 ( H ) .

"

Huong

)(H).

B. lOOV.

D . 0,2/7t ( H ) .

'

' '

= . I = H K . f ^ . , ( A ) ^ Z , = H k = ^ = 30=>L = ^ = M ( H ) = . C h o n B .
R
40

^ ^
I
1
M
71 ^ ^

i
C. 25 V .

Huong

dan

'

-

hieu d u n g tren bien tro la

A.50V2 V .
C. 0,4/(7i

50^ =ul+ 30^ r:> U K = 40(V)

U^ = U | + U ^

40V. D i e u chinh de gia trj bien tro Ion gap doi so v o i luc dau thi dien ap

UR=50(V)

Z c = l , 8 R = 0,9R'

UL

-40(V)

Z L =0,8R = 0,4R'

Ue

=90(V)

jiji =

D.

20V1OV.

dan

•^?-M,;>vt.h^r.5i
, ,

U = Juf^+(UL-Uc)

=V50^+(40-90)2 = 5 0 V 2 ( V )

V i du 12: Cho mach dien xoay chieu k h o n g phan nhanh RLC, cuon day thuan
H

cam va Zi, = 8R/3 = 2Zc. D i e n ap hieu d u n g giiia hai dau doan mach la 200

U^ = U

'I + ( U

V . Dien ap hi§u d u n g giiTra hai dau dien tro R la

=>U'K

=20VT0(V)=:^Chon D .

A . 180 V .

r*

r;

B. 120 V.

C. 145 V .

'L - U

c )^ => 50^2

= U

+

(0,4U

'K -

0,9U

'K ) ^

D . 100 V.
27


Bo

trg kie'n thitc

V^t IILTDH

trSn hcnh

VTV2. t^p 2 - Chu VSn Blen

_ _ _ _ _ _

V i d u 15: M o t macii dien g o m m o t cuon day ccS dien t r o thuan r he so t u cam L
noi

tiep v o i m o t tu dien C d u o c mac vao m o t hieu d i e n the xoay chieu.

Cty T/VHH fllTV D VVH

Kbang

thoi h a i d a u doan mach A B bang +0,5Uo va dien ap tiic t h o i tren L bang
+UOL/72 . D i e n ap giua hai d a u doan mach

Cu'ong d o hieu d u n g cua d o n g dien qua mach d o d u g c I = 0,2 A . H i e u dien

A. s o m pha h o n d o n g dien la 7i/12.

B. s o m pha h o n d o n g d i e n la 71/6.

the hieu d u n g giua hai dau doan macii, gifra hai dau cuon day, giira hai ban

C. t r i p h a h a n d o n g dien la 7t/12.

D . tre p h a h a n d o n g d i e n la 71/6.

tu dien c6 gia trj Ian l u g t la 120 V, 160 V, 56 V . D i e n t r o thuan ciia d a y la
A. 128Q.

B.480£l

>Kii,

.Si : • < • ' : H u a n g d d n

= U? + ( U L

- UCf

C. 96 Q .

= U? +

Huong

u = U() cos(())t + (p) = i ^ = > (rot + (p) = ± —

.

= U ^ L - ^^L^c

r =^

+ Uc

>

U = U()L COS rot + —

2,

=480(Q)=>ChonB.

7t

^ « ' ^ ' ^ ^^-^

(o)l+(p)<

(rot + cp) = - -

2

'

A.30Q.

^'''"> «

B.25Q.

C.20Q.
Huong

2,

'

phahcfn

i => C h o n C.

n
4

}/: Niju cho gid tri tire thai dien dp a hai tlwi diem tin van c6 the tinh duvc cp.

V i d u 18: M a c h d i e n xoay chieu noi tiep A B tan so 50 H z g o m d i e n t r o thuan R,

J \

"

Chu

_^ 71

rot + —

i? = -—<0:utre
rot + —

doan mach g o m dien t r o R noi tiep v o i cuon day c6 he so t u c a m L = 0,12/7:
(H) va dien t r o thuan 9 Q t h i di§n ap hi?u d u n g tren R la 5 VS V . H a y t i n h

3

72

•

2)

V i d u 16: D a t m o t dien ap u = 20 ^y2 coslOOrtt (V), (t do bang giay) vao hai dau

dien t r o R.

2

U OL

i = In c o s w t :

120^ = 160^ - 2 U L . 5 6 + 56^ => U L = 1 2 8 ( V )
1602=U?j=U?+U[=i>Ur=96:

dan

D . 300 Q.

..^

- 2ULUC +

Vl^t

cuon cam t h u a n L va t u dien C (R, L , C khac 0 va hi>u han). Bien d o ciia

D.15Q.

d i e n ap g i u a h a i d a u doan A B va tren L Ian l u g t la Uo v a Uoi,. 6 t h a i d i e m t i

dan

dien ap t u c t h o i giua hai d a u doan mach A B bang +0,5Uo va sau khoang
U,

r
= (UK +

R

UR

U,
Chu

3

3
U,f

-=^R
3

t h o i gian ngan nhat 1/400 s dien ap tuc thoi tren L bang +UQI./72 . D i e n ap

'

g i i i a hai d a u doan mach

x2 1 6 ,
+ U [ = > 4 0 0 = (5>/5 + U , ) ' + ^ U ? => U , = 375 ( V )

A. s o m pha h o n d o n g d i e n la 7t/12.

B. s a m pha h o n d o n g d i e n la 7t/6.

C. tre pha h o n d o n g d i e n la 7i/12.

= - r = 1 5 ( Q ) = > C h o n D.
3
^ '

D . tre p h a h a n d o n g d i e n la 71/6.

Huong

,t: ,jQ

y: Co the can ci'c vao gid tri tiir thai tinh do lech pha.

dan

u = UQCOs(rot + (p)

•

' ' •

i = I()COSrot:
^,f,V, •/()<•' ,,VOr. jiJ

UL

u = UoCos(cot + (p)

u =U
71

i = iocosa)t=> U1 = U()L COS (Ot + -

. Khi cho biet cdc gid tri tuc tiioi

2,
VAi;V,S)*

uc=U„cCos

UL

= U 2

UQ

- U3

u = UoCos(l007rti +(p) =

U = U Q L COS IOOTI

M t - -

2.
l

2v

71

chon dau avig hoqc trif dc'sno cho

(ot--

l

'

-u.-. ,

vd phdi km

2
7t

<((ot

+ ( p ) < cot + —

2

2J
Tit do se tiin du'o'c
=

mt--

;'•

•

rot + 2

|

n

thi ta se tun dinrc (cot + (p) = i a j ; mt + -

= U O L COS

•

V i d u 17: M a c h dien xoay chieu n o i tiep A B g o m dien t r o thuan R, cuon cam

Uo
1

ti +

+

400

7t

U, OL

2

72

—

1007rt + ^ + i ^
4 2

\,,

• (p = — > 0 : u s6m hdn i la — => Chon B.
6
6

7t

,,.r,,.vi

Chii 11: Ne'u cho gid tri dien dp tuc thoi vd dong dien a hai thai diem tinh dugc
u = Uo coslOOTit-

u=uo

va u gidm

(tang)

i = lo cos(1007it - ( p ) - - _ - i ^ It=to+At

Q^^l"

1 = 0 vdigiam

-»roto = ?
->(p = ?

(tang)

^

* A

thuan L va tu d i e n C (R, L , C khac 0 va hCru han). Bien d o cua dien ap giua
hai
98

d a u doan A B va tren L Ian l u g t la Uo va UOL. 6 t h o i d i e m t d i e n ap tuc
29


Cty TISHH nrv
Bo trp kien

thiic

V^t liLTDIl

VTV2. t^p 2 - Chu

tren henh

VSn

u = I()Zcos(cot +

V i dy 19: D a t di§n ap 200V - 50Hz vao hai dau doan mach A B g o m dien t r o
t h u a n 25^2 mSc n o i tie'p v o i doan mach X. C u o n g d o d o n g d i e n hieu d u n g

^

t=to

;

b) N e u cho u = U,)Cos(cot + (p^,) t h i i = -^cos(a)t + ip^ - (p). ',

Huang dan
u = 200 Lid u tang

;

" M N =IoZMNCos(cot + ( P i + 9 M N )

ap giua hai dau doan mach A B so v o i d o n g d i e n qua mach va cong sua't tieu

u = 200^/2coslOOTtt-

. xiU •

U c =IoZ(;COs(cOt + (Pi - 7 l / 2 )

tuc t h o i qua doan mach bang 2 A va dang g i a m . T i n h do lech pha ciia dien

...ft;.,

+ cp)

a) Ne'u cho i = Iocos(cj)t + cp;) t h i U L =IoZLCos(cot + 9 j + 7 i / 2 )

CO gia t r j 200V va d a n g tang; 6 thoi d i e m to + 1/600 (s), c u o n g d o d o n g dien

„•-,,,,,.•

Vi^t

U ] ^ =I()Rcos(cot +
qua doan mach la 2 A . Biet 6 t h o i d i e m to, dien ap ti'rc t h o i g i u a hai d a u A B

thu dien cua doan mach A B va doan mach X.

DVV11 Khang

Bien

' ' t • ' •

.

-^lOOTito = - -

c) Ne'u cho u ^ N = UoMNCOs(a)t + a ) t h i i = ^ ' ^ ^ cos(o)t + a - tp^N ) •
Sau k h i vie't d u o c bieu t h i i c ciia i se vie't d u g c bieu thuc cac d i e n ap khac

i=2^/2cos(1007^t-(p)-

i = 2vd \

IOOTI

tn+-

600

-9

71

theo each l a m tren.

4

V i du 1: M o t mach dien xoay chieu mac noi tie'p g o m dien tro t h u a n R = I S Q ,
cuon thuan cam c6 cam khang Z L = 25Q va t u dien c6 d u n g k h a n g Zc = lOQ.

=> (p = - — < 0 : D i e n ap U A B tre pha h o n i la 7:/3.
C o n g suat tieu t h u d i e n cua doan mach A B va doan mach X Ian l u g t la:

ti

P = Ulcoscp = 200(W) va Px = P - l^R = lOO(W).
V i du 20: ( D H - 2012) Dat dien ap u = 400cosl007tt (u ti'nh bang V, t t i n h bang s)
vao hai dau d o a n mach A B g o m dien t r o thuan 50 Q mac no'i tie'p v o l doan

Ne'u d o n g d i e n qua mach c6 bieu thuc i = 2 V2 cos(1007rt + 7c/4) ( A ) t h i bieu
thuc dien ap hai dau doan mach la

t + 1/400 (s), c u o n g d o d o n g dien tuc thoi qua doan mach b a n g k h o n g va
d a n g g i a m . C o n g sua't tieu t h u dien cua doan mach X la
A. 400W.

B.200W.

C. 1 6 0 W .
Huang

u = 400cosl007Tt

t=o

i = 2V2cos(1007tt-(p)-

D. lOOW.

dan

400

i = Ova \

=P-Pj^ = Ulcos(p-I^R = 2 0 0 ( W ) :

C. u = 60cos(1007tt-7i/4)(V).

D . u = 30^/2cos(1007ct-7r/2)(V).
Huang

Z L

Zr

= ft)L =
=

1
coC

25Q

= 10Q

Z = ^/R2+(ZL-Zcf
tancp =

IOOTT.-

U

01.

R

Z = VR^+(ZL-ZC)ZL-ZC

tanq) = •
30

R

U oc

400

Chon B.

R

7t

= l = > ( p = — > 0 : u sdm hon i Id —
4
. ,. ...4,
7C

Chon A .

(V):

g i i i a hai dau doan mach chiVa cuon day va t u d i f n.

A . ULrC = 60cos(1007it - 71/3) (V).

B. ULrC = 60cos(1007it + 7l/4) (V).

C. U L r c = 6 0 V 2 c o s ( 1 0 0 7 : t - 7 t / 1 2 ) ( V ) .

D . U L ^ C = 60 V2 cos(1007it + 57r/12) (V)

Huang
ZtrC =

U OMN

Zc

+ ( Z L - Zc f

tan(pLrC = ?^

ZMN
- Z

tancpMN =

- Z

bieu thuc i = 2cos(1007:t + 7t/6) (A) (t d o bang giay). Viet bieu thuc dien ap

Viet bieu thirc theo phimng phdp truyen thong:
U OR

Z,

= 1572

• u = IijZcos'l007rt + ^ + ^ l = 2V2.I5V2COS 1007rt +
4
4J

2) B i e u thiic dong di^n va di^n ap
Un

dan

30Q va CO cam k h a n g 40Q, t u dien c6 d u n g k h a n g lOQ. D o n g m g c h chinh c6
7t
n
= -=>(p = —
2
4
4-,.i V'V:''

Io =

. .r

V i du 2: M a c h dien xoay chieu g o m dien t r o 30 Q, cuon day c6 d i e n t r o thuan

>u = 400 ( V )
t=o+

'

B. u = 30 V2 cos(1007it + 7r/4) (V).

mach X. C u o n g do d o n g dien hieu d u n g qua doan mach la 2 A . Biet 6
t h a i d i e m t, dien ap tuc t h o i giua hai dau A B c6 gia t r i 400 V ; 6 t h a i d i e m

. , ,

A . u = 60cos(1007tt + 71/2) (V).

MN

R MN

-z

/

r

=1
r

dan

= 30V2Q

=> cpLfP = — >

HI lu.
0 : ULrC

h^'^ ^

4

,

~
4

57t
(V)
" L r C =IoZLrCCOS 1007rt + ^ + ^ = 60^y2(cos 1007tt +
12
6
4,
• C h o n D.
31


Cty
Bo trp klSn thiic

V^t li LTDH

trcn

henh

VTV2,

t4p 2 - Chu

V0n

Vi du 3: Mot cuon day thuan cam c6 do tu cam 1/n (H) va tu dien c6 dien
d u n g 2.10-'/TI (F) ghep noi tie'p, roi no! hai dau doan mach vao nguon c6
dien ap u = 100 V2cos(1007it + Tt/6) (V). Dong dien qua mach la
A. i = 2cos(1007it + 71/2) (A).

C. i =2 ^/2 cos(100Ttt - 71/3) (A).

D. i = 2 V2 cos(1007Tt + 7t/2) (A).

Huong dan

w o r b w^l/i (cf

"ri'T,''!' *• ^••••I'rrin'J

wC

Z=

+(ZL

tan (|) = Z, - Z r

—1^ 0

.

U,

= 50Q

-Zc)^

=

-

7t

irii (o + }fc)r!',o,.^f,,,,0

,„>^fU

or!'; ir^VI (./

. , TT •jV'ub ,h>*v
sC/n p/ia /iCw ila— ,
, ,

+cx)=>(p = — > 0 : i i

U68

2 .H'-iii iBfil-'i^r,:* canJ
(A)=>Chon
C.
6 2,
Vi du 4: Mot doan mach gom cuon day c6 do tu cam 0,6/7i (H) mac no'i tiep vai
mot tu dien c6 dien dung 1/(14?:) (mF). Dat vao hai dau doan mach mot
dien ap xoay chieu c6 bieu thuc: u = 160cos(1007it - 71/12) (V) thi cong suat
tieu thu trong mach la 80 W. Bieu thuc cuong do dong dien trong mach la
A. i = 2cos(1007it - 7i/6) (A).
B. i = 72 cos(1007tt + n/6) (A).
C. i = V2 cos(1007:t + 7i/4) (A).
D. i = V2 cos(1007it - 7c/4) (A).
, ,
Huong d^n
. ^ ^
7t

-COS

1007rt +

ZL =(OL = 60(Q);Z(-. =
.A auii

U^R

7t

lOOTTt--

. 2

3.

= 140(Q)
coC • A i l

.,•1"

\y.o

• => 80 = •
P = I^R = R^+(ZL-Zcf

•"it

tanq) = —
Z=

R

80-.2.R

4

• 1 ' ) )

R = 80(Q)

pha han i let —(i sdm pha hcfh u)

4

+ ( Z L - Z ( ; ) ^ = 80>/2 ( Q )

i i = — c o s lOOTTt- — + - =V2icos 1007tt + 12 4

(A)=>Chon B.
6J + 7t/4) (V) vao hai dau doan
Vi du 5: Dat dien ap xoay chieu u = 10cos(1007it
mach noi tie'p gom mot tu di^n c6 dung khang 30Q, dien trd thuan R = lOQ,
va cuon day c6 di^n tra thuan lOQ c6 cam khang lOQ. Viet bieu thiic di^n
ap giiia hai dau cuon day.
A. ucd = 5cos(1007it + 37C/4) (V).
B. ucd = 200 ^/2 cos(1007tt + n/6) (V).
C. Ucd = 200cos(1007tt + Tc/6) (V).
D. Ucd = 5cos(1007it + 7t/4) (V).

f9.

32

ZL-ZC

Vift

= 2 0 V 2 ( Q ) z,d =Vr^Tzf = ioV2(n)

,

n

tanked = — = l=>(Pcd = 7

r

Bieu thuc u^d som hon u la cp^j -(p = ^ vaUocd

= ^ ' ^ c d " ^^^--^^"^

4

=

^(^)

371

Dodo: u,a =U(,cdCos
4 2 = 5cos 1007lt + (V)=^Chon A.
Vi du 6: (DH-2009) Dat dien ap xoay chieu vao hai dau doan mach c6 R, L, C
mSc noi tie'p. Bic't R = 10 Q, cuon cam thuan c6 L = 0,1/71 (H), tu dien c6
C = 0,5/7t (mF) va dien ap giita hai dau cuon cam thuan la
^^
ui = 20 V2 cos(l 007it + 71/2) (V). Bieu thuc dien ap giira hai dau doan mach la
A. u = 40cos(l OOTtt + 7t/4) (V)
B. u = 40cos(1007ct - 7t/4) (V)
C. u = 40 N/2 cos(l 007it + 71/4) (V)
D. u = 40-Jl cos(1007it - 7:/4) (V)
Huong dan
^

Z, =coL = 10(Q);Z(;- =

^

=

20(0)

[Z = 7 R ' + ( Z L - Z C ) ' = 1072fi

71

z,-z.

- ^ = -l=>(n =

7:

^^'.^fa'^"

tan (p = R
4
Dien ap u tre hon i la 7r/4 ma i tre pha han UL la 7r/2 nen u tre pha hon U L la
-Z = 40(V).
371/4 va U(, =
z,

..r i

+(60-140r

^ = -1 =>q) = — <0:utre

MTV !> V VII Khang

Huang dan

Z = ^{R + rf+{Z^_-Zcf

B. i = 2cos(100Tit - 7t/2) (A).

Z, =wL = 1 0 0 Q ; Z c = — = 50Q

Timn

Blen

Do do: u = UnCos

(

1007Ct+

n 3n^

f

A (V)^ChonB.

= 40cos l O O T t t - -

2
4 y
;
Vi du 7: Doan mach Ixoay chieu
khong
phanl nhanh 4gom
cac phan tu theo dung
thu tu: dien trd thuan 30 (Q), cuon day thuan cam c6 do tu cam 0,6/7c (H) va
tu dien CO dien dung IOO/TI ().iF). Dien ap giiia tren doan mach chi gom cuon
cam va tu dien c6 bieu thuc ULC = 160cos(1007rt - 7t/3) (V) (t do bang giay).
Bieu thuc dong dien qua mach la
A. i = 4V2 cos(1007tt + 7t/6) (A).
B. i = 4cos(1007tt + 7t/3) (A).
C. i = 4cos(1007tt - Ti/6) (A).
D. i = 4cos(1007tt + n/6) (A). : ih : '
Hudtigdan
'-.} ./

ZL = w L = 60Q;Zc =

tancpL^; =
hon)

Z, - Z

= 100Q; ZLC = ^ 0

- ^ C ) = 40<^

• (PLC = - — < 0 : U L C tre P^a

hon i la 7i/2 (i som pha


B S trp klih

thiic

V^t It LTDtl

tr&n k6nh

100Kt---(pLC

=> 1 =

Cty TlSHtlnrvDVVHKhang

VTV2. t$p 2 - Chu VHn Bien

= 4cos lOOrtt-

(A)=>Chon D.

V i du 8: (DH-2010) Dat dien ap u = Uocoscot vao hai dau doan mach gom dien
tro thuan R, cuon cam thuan c6 do tu cam L va tu dien c6 dien dung C mac
noi tiep. Goi i la cuong do dong dien tuc thoi trong doan mach; u , , U 2 va

V i du 11: Dat dien ap u = U(icos(cot + 7i/4) (V) vao hai dau doan mach gom dien

tra thuan R va cuon cam thuan c6 do tu cam L mac no'i tiep thi cuong do
dong dien qua doan mach la i = Ii)sin(ci)t + 57r/12) (A). Ti so dien tro thuan R
va cam khang cua cuon cam la
A. 1/V3.
B. 1.
C.0,5V3.
D. V 3 .

Huong dan

U 3 Ian lugt la dien ap tuc thoi giira hai dau dien tro, giua hai dau cuon cam
va giCra hai dau tu dien. He thuc dung la
A. i = -

\

•

^

^

R2 + coL -

. •.

(oC

D.

i=

— ^ Chon C.

V i du 9: Mot doan mach gom cuon day c6 dien tro thuan 100 Vs Q, c6 do tu
' „ cam L noi tiep voi tu dien c6 dien dung 0,00005/7t (F). Dat vao hai dau doan
mach mot dien ap xoay chieu u = Uocos(1007rt - Tt/4) (V) thi bieu thuc cuong
do dong dien tuc thoi qua mach i = V2 cos(1007tt - 7c/12) (A). Xac djnh L.
,

. A. L = 0,4/71 ( H ) .

B. L = 0,6/TI ( H ) .

4
cot +
12

= locos

n

C. L = 1/n ( H ) .

D. L = 0,5/:: ( H ) .

Z L = lOO(Q) =0 L = - ( H )

1
ZL-200

_
L
V3
IOOV3

Chon C.

noi tiep gom dien tro R = 50 Q, cuon cam thuan L va tu dien C thi dong dien
•'V; i ' qua mach c6 bieu thuc i = 2 V2 cos(1007rt + 7t/4) (A). Goi U L va

= 50V2 V.

Ian luot

D.UC-UL

= 100V2 V.

B.6V5V.

C.30V2 V.

D. 60 V.

R

= t a n — = > U C - U L = 100(V)
IR

R

1

Cdch 1:
; I2 ^ = 3 1 , ; i j som pha hon u;

-2C

U2LC = U 2 L - U 2 C = U l R z O 3 Z L - ZC = R

UILC = U I C - U H . = U2K r : i > Z c - Z l , = 3 R

12 tre pha hon u;

I , 112.

(1)

(2)

Tu (1) va (2) => Z L = 2R; Zc = 5 R
Ban dau

tan ( - c p i ) =

ZL-ZC

r-

u OKL Z =

Z RL

VR"

- X J R ^ + ( 2 R - 5 R ) ^ =60(V) =>ChonD.
+4R

^

^

Cdch 2:

Huong dan
(p = -

n

A.I2V5V.

Uo = I„Z =

B. Uc - U L = 100 V.
^,

12 y

V

V i du 12: Mot cuon day khong thuan cam noi

tiep voi tu dien C trong mach xoay chieu c6
dien ap u = Uocoscut (V) thi dong dien trong
mach s6m pha hon dien ap u la c|)i va dien
ap hieu dung giira hai dau cuon day.la 30 V.
Neu thay C i = 3C thi dong dien cham pha
hon u goc c|)2 = 90" - c|)i va dien ap hieu dung
giua hai dau cuon day la 90 V. Tim Uo.

, la dien ap hieu dung tren L va tren C. He thuc diing la

C.UL-UC

2,

chieu cua 0 tren I la 0,^

V i du 10: Dat dien ap xoay chieu u = U V2 coslOOnt (V) vao hai dau doan mach

A. U L - Uc = 100 V.

12

/

= I„cos M t -

Huang dan

1 r.r.r.,^^
^

Zr-Zc
- (oC = 2 0 0 ( f i ) ; 9 = 9^,-cpi = — =>tan(p = - ^ R c _

^

n

Z,

Huang dan
"

on
(Ot +

75
(oL

•;'ir-: Chu y: Neu eho biet bieu thuc u, i thi ta se tinh duge trakhdng.

•

,

03t + —

ftifi .'.pil ^opt "^hn

Huang dan
Chi Ui Cling pha vdiineni-

U = UyCOS

i = I n sin

. I ' i (>,f'i/ ;.j';Hn

Vl^t

Zi - Z r

<- 0 =>

-~ =t a n (Pi

ZC-ZL

Chon B .

R
/ J

4

Chu ij: Neu c6 dang sin thi doi sang dang cos: sin (cot + a) = cos cot + a —

2.

= IZ„, = u

R^+Z
'R-+(Z,-Zcf

= 30

W4 A)

Hinh


tUi trp kiSn thiic V$t IILTBH

Cty TISHll nrv DVVH Khang

trSn henJt VTV2. t4tp 2 - Chu VSn Blen

Vlft

= 90
K

K
^-MN

ZMN

Z M N

T h e o b a i r a : 9 1 + 9 2 = 9 0 " n e n tan(pitan(p2 = 1 h a y
B i e u t h i i c d o n g d i e n : i = =• = —

^

' ^ ^ ^ ^ = 1 => R = J ( Z c - Z L ) ( Z , - Z c / 3 )
Cai dat tinh toan vai sophitc
Zc^

U'

cd

U

cd

z, - " ^

R2+(ZL-Zcr

3 ;

Z,

R2 +
(ZC-ZL)

-

(ZC-ZL) + (ZL-ZC)'

z, -

(ZC-ZL) +

= 3 =^ Z c = 2 , 5 Z L ^ R = 0 , 5 Z L

,

Zc^

j.^;

+

90

+

^.^^^^ .gj.^

j

Zr

ZMN

trong may tinh casino fx-570es

!_ ( D e cai datt t ti i n h toan v d i s o p h u c )

B A M M O D E

B A M

30

••MN

Z,

V

SHTFT M O D E

B A M SHTFT

( D e cai dat h i e n t h i so p h t i c d a n g A Z 9 )

4 ( D e cai dat d o n v i goc l a r a d ) .

M O D E

1) l ^ n g d u n g v i e t b i e u t h u c
V i d u 1: D a t m o t d i e n a p x o a y c h i e u u = 200cos(]007it + 7i/3) ( V ) v a o h a i d a u
m o t d o a n m a c h m a c n o i tiep g o m t u d i e n co d u n g k h a n g 50Q, d i e n t r o

T h a y g i a t r j n a y v a o b i e u t h u c UCJ:
, ,fl

t h u a n 5 0 Q v a c u o n c a m t h u a n c o c a m k h a n g lOOQ. T i n h t o n g t r o c i i a m a c h .
D i e n a p giCra h a i d a u d o a n m a c h s o m h a y t r e p h a h o n d o n g d i e n t r o n g

(0,5Z,,)^+Zf^

= 30=>Uo = 6 0 ( V )

mach bao nhieu? Viet bieu thuc d o n g dien trong mach.

V2^(0,5ZL)'+(ZL-2,5Z,J

Huang dan
BAI TOAN LIEN QUAN DEN BIEU DIEN

PHl7C

Ccich 1: Cdch truyen

Dang phuc trong may

Bi'eH thuc

FX-570
Tong tro

tancp =

f f n ' n . j i :J5
= A/I^MN + ( Z L M N

" Z C M N

)

Z M N

= I^MN + ' ( Z L M N

Zl - Z p
R

- 50V2 ( Q )

^

7t

„

,

. , v 'V

4

4

. 200
=
c o s 1007rt + ^ - ^ = 2^/2 cos
3 4,

~ ^ C M N )

t

= lr=>(p = — > 0 : u sdm h d n 1 la —

1

( v o l i la s o a o )

Z M N

Z = ^R^ + ( Z L - Z C f

Z = R + i(Z, - Z ^ )

Z =7R^+(Z,,-Z,)^

thong

1007tt +

n
12

i t r e h d n u la —
4;

(V)

Cdch 2: Dung mdy tinh cam tay casio 570es

Z i . = Z, i , Z e = - Z ( _ i

Cai dat tinh toan vai so phuc trong mdy tinh casino fx-570es

( v o l i la s o a o )

+

B A M [ M O D E | g ( D e c a i dat t i n h t o a n v 6 i s o p h u c )

'

Dong dien

i = IQ cos(iut + (P| )

i = I(,Zcpi

+

B A M ^ H T F T [ ^ 0 D E | 0 g §](De

Di^n

u = U(, cos (cot + cp^,)

u = UoZcp,

+

B A M ^ H T F T | ^ 0 D E | Q ( D e c a i dat d o n v i goc l a r a d )

Dinh

ap
luat

6m

,
U
^
I = — nhiina
Z

cai dat h i ^ n t h i so p h u c d a n g A Z (p)

Z = 50V2(O)

u

. u
i =A —
Z

Z = R + i ( Z L - Z c ) = 50 + 1 ( 1 0 0 - 5 0 ) = 5 0 7 2 Z - « ^
• I-'MN

-

'^un

Z M N

U = I Z nhi/ng

>

11 7^ i Z

Z M N

= I Z ^ 4 N n/if/n^ " M N ' ' Z M N

LIMN

3

R+i ( Z L - Z c )

50 + 1 ( 1 0 0 - 5 0 )

= ^Z^N

u

" y
" M N

200Z-

UoZcp,

u = iZ
Z

U M N

''

=

g'^MN

0

1 = 2N/2COS

1007lt +

n
12

(A)

=272Z-^
12

71

•V


Cty T/SHHnrvDVVHKhang
B6 trg klS'n thiic V$t li LTOH

tren henh

H i e n t h i tren m a n h i n h

Thao tac

CMPLX

[5^R[ENGl0plOOlR^[)]R| SHIFT I ^ ^ R

R

Math

4)

UcL

= l^CL

- - S - ^ C L

50 + i ( 1 0 0 - 5 0 )

i

i.'.A'''

•.'•lA^

^

50V2Z-7r
4

CMPLX
SHIFT (-)

SHIFT

xlC* V

•
•

• .J.i;;^"j,

y iim^Jt^.*

••'f.Mv

3 >

+ A n s SHIFT 1213

=

R

Math

200Z-^Ans
3
•

=220cos lOOTtt-

12

(V)

cuon thuan cam c6 cam khang Z L = 25r} va t u dien c6 d u n g khang ZQ =

H i e n t h i tren m a n h i n h

Thao tac

UQI

-

220^/2Z ^^
(0 + 1(50-100)) =220Z —,
50 + 1(50-100)

12

v i d u 3: M o t mach dien xoay chieu mac noi tie'p g o m dien tro t h u a n R = 15Q,

T o n g t r a la 50 \/2 Q va d i e n ap som pha hon d o n g dien la n/4.

200

'

lOO. N e u d o n g dien qua mach c6 bieu thuc 1 = 2 V2 cos(100Tit + 7t/6) ( A ) t h i
bleu thuc dien ap gii>a hai dau doan mach la
A . u = 60cos(l OOKt + 571/12) (V).

B. u = 30 V2 cos(1007it + 7i/4) (V).

C. u = 60cos(1007rt - 7i/4) (V).

D . u = 30 N/2 cos(1007rt - 57r/12) (V).

2^/2Z — TC
12

Huong dan
u = i.Z = 2 V 2 Z - ] x ( l 5 + i ( 2 5 - 1 0 ) ) = 60Z —
6y
12

Bieu thi'fc d o n g dien i = 272 cos 100Trt + — ( A )
12

V i d u 2 : Dat dien ap xoay chieu u = 220^/2 cos(1007it + n/3) (V) vao hai dau
"doan mach theo d i i n g t h i i t u g o m dien tro thuan R = 50Q, tu dien c6 dien
d u n g C = 100/7i()j,F) va cuon cam thuan c6 do t u cam L = 0,5/7r(H) mac noi tie'p.
1) T i n h tong t r o ciia mach. D i e n ap giiia hai dau doan mach som hay tre
pha h o n d o n g dien trong mach bao nhieu?
3) Viet bieu thuc dien ap 6 hai dau chua R va C.
4) Viet bieu t h i i c dien ap 6 hai dau chua C va L .

v;. i, J"''?!'

Huong dan

v
" '

Bam
Tren

Bam
Z = 50V2(Q)
7t

'~Z

220>/2Z-

UoZcpu

3

= 4 , 4 Z ^ . .
12 •
~ R+ i ( Z L - Z c ) "50 + i(50-100)

i = 4 , 4 cos lOOTCt-

7K

12

(A)

2j~

SHIFT

man hinh

(-) 3 0 y ( |15|| + ||ENG| ( 25

272Z30 x (15 +1(25 - 1 0 ) )

'

Z

:

^ ( 5 0

50+ 1(50-100)^

U R C = 491,935cos(1007rt + 0,725)(V)

+ UO - 1 0 0 ) ) « 491,935Z0,725
^

'

11*' r

'

10 ) )

{

|2N/2||SHIFT1[(-)

30[xj ( |15||+||ENG| ( [ 2 5 j y [ l 0 j ) )

1H

ISHIFTI [(+)J R se dUdc UQ = 60. Bam |SHIFT| 9 se dMc cp^, = 75.

V i d u 4: M o t doan mach d i e n xoay chieu noi tie'p theo d i i n g t h u t u g o m cuon
cam t h u a n L c6 cam khang 30Q, dien t r o R = 30Q v a t u d i e n C c6 d u n g
khang 60Q. D o n g qua mach c6 bieu thuc 1 = V2 cos(1007it + nl6) ( A ) . Viet
bieu t h u c d i e n ap glQ-a hai d a u doan mach chiia LR.
A . U L R = 60cos(1007ct + 57r/12)(V).

B. U L R = 60^/2 cos(100Kt + 57r/12)(V).

C. U L R = 60V2cos(1007rt-7t/3)(V).

D . U L R = 60 >/2 cos(1007it + 7r/3) (V).

Huang dan
" L R

220N/2Z3 ) U R C = iZRc = " Z R C =

(V)

60Z75

Bam

T i n h t o n g t r o ciia mach la 50 yfl Q; dien ap tre h o n d o n g d i e n la 7i/4.
_

12

Fx - 5 7 0 M S :

Z L =coL = 5 0 ( Q ) ; Z e = — = 100(Q)

o\ _

5TC

FX-570ES:

t

. ^, •.^.'''r''

1 ) Z = R + i ( Z L - Z c ) = 50 + i (50 -100) = 5072Z - <=>

u = 60cos 1007lt +

=> Chon A .

2) Viet bieu t h i i c cua c u o n g do d o n g dien tiic t h o i qua doan mach.

^

Vift

VTV2. tap 2 - Chu VSn Bien

= I-ZLR

=

5%
^ V 2 Z - 1 X ( 3 0 + 1 ( 3 0 - O)) = 6 0 Z 6J
12

= > U L R =60COS

So07rt + — ( V )
12

Chon A .

'
39


Cty
Bo

trg kicn thiic V^t IILTDII
Fx - 5 7 0 E S :

Bam

trcn Renh

%rrV2. t^p 2 - Chu VSn Bl£a

2 > SHIFT ( - ) 30

ENG

30

D i e n ap 6 hai d a u doan mach u = 1 6 0 V2 coslOOTit (V). Viet bleu thuc d o n g
d i e n qua mach va t i n h dien ap hieu d u n g

30

60Z75
Fx -

570MS:

2 SHIFT ( - ) 30

Bam

30

ENG

I SHIFT I [(+)| [=] se duac C/,„ ^ = 60. Bam

Bam

' ' •'

i'Sjii: ' i t i r f f u-:il?1'">''\,'i~<,^>;' £>''::i.iij -liii'ttK ' N ' M

rT:"ji:1:vft'io;:;

•'•]. 'iiS'':

[SHIFT | y se (fu^tfc cp^^

B. i = 2N/2 cos(]OOTit + n/4) ( A ) va URL2 = 6 0 (V).
C. i = 4.cos(1007tt - 71/6) ( A ) va U R L J =

=75.

tren d o a n mach la 440 W . Bieu thuc c u o n g do d o n g dien qua doan mach la
B. i = 2 V2 cos(100Trt + 7i/4) ( A ) .

C. i = 4cos(1007rt + K / 4 ) ( A ) .

D . i = 2 N/2 cos(1007tt - 7i/4) ( A ) .
Huang dan

y-'-

U-R

p = rR =

•440 =

220\55
55^ + Zc

:

,•••/'<-

Ze=55(Q)

22072

u

= 4Z —T: <=> i = 4cos 1007lt + - ( A ) i ^ C h o n C .
4
4,
d u 6: M o t doan mach g o m cuon day c6 dien t r o thuan 100N/3 Q , C6 d o t u

" Z " 55+1(0-55)

Vi

cam l/n

( H ) n o i tiep v o i t u dien c6 dien d u n g 50/TC ().iF). Dat vao hai dau

d o a n mach d i e n ap: u = 200N/2 cos(]007it - TC/4)

( V ) . Bieu t h i i c dien ap tiic

ZL,

A.

u , d = 200 ^/2 cos(1007rt + 7t/12) ( V ) .

B. u . ^ = 100>/2 cos(1007it + 7r/6) ( V ) .

C.

u^d = 200 N/2 cos(1007tt + n/6) ( V ) .

D . u . ^ = 100 ^/2 cos(1007ct + 7:/12) ( V ) ,

•g/vju

Huang

[ Z , = c o L = 100(Q)
Zc =

coC

^

<=> u^H = 200V2cos

12

=«L2

=30(Q)

z

1
= 4 Z - - 7 : » i = 4cos lOOnt
' " Z ~ 4 0 + i ( 1 0 + 30)
4

I

I6OV2

U K L 2 = I-ZRL2

= 2V2.5O = 100V2 ( V )

71

— (A)
4

Chon D .

^

V i d u 8: Cho mach dien xoay chieu gom dien tro thuan R , cuon day thuan cam
L va tu d i e n C = 1/n mF

mac noi tiep. Neu bieu thuc ciia d i e n ap giCra hai

ban t u dien la Uc = 50%/2

cos(1007Tt - 37T/4) ( V ) t h i bieu t h i i c ciia c u o n g do

d o n g dien t r o n g mach la

^

' i ^ ^ ' ^ ' - ' ^ " ^

f-^-'

A. i = 5 V2 cos(1007rt + 37r/4) ( A ) .

B. i = 5 x/2 cos(1007:t) ( A ) ,

C. i = 5N/2cos(1007rt-7r/4)(A).

D . i = 5cos(100Trt - 37i/4) ( A ) .

-

!

Huang

dan

=J-.IOQ
(oC

u
50^/2Z-^^
=>i = ^ =
^ = 5x/2Z--7r
Z
0 + i(0-10)
4

Z = 0 + i(0-Zc)
lOOTlt--

(A)=>ChonC.

V i du 9: M o t doan m a c h xoay chieu noi tiep A B g o m d i e n t r o lOOQ, cuon cam

b a n g giay). Bieu thuc d i e n ap hai dau doan mach A B la
200-j2Z~n

A. u = 100 V2 cos(1007rt - 1171/12) (V).

B. u = 100 V2 cos(1007tt + ll7t/12) (V).

C. u = 50cos(1007it + 7t/12) (V).

D . u = 50 N/2 cos(1007tt + 7t/12) (V).

( V ) => Chon A.

t h u a n 1 CO d o t u cam L i = 0,1/?: ( H ) , d i e n t r o t h u a n 40 Q. va cuon cam t h u a n

/in

Z = R + i(ZL-Zc)

Huang

du 7: Cho d o a n mach xoay chieu noi tiep theo d u n g t h u t u g o m cuon cam
2 C O do t u cam L2 = 0,3/71 ( H ) .

.

t h o i gii>a hai d a u cuon cam c6 bieu thiic ui. = 100cos(1007Tt - 7T/6) (V) (t do

200N/2Z-~

1007tt + -

;

t h u a n CO cam khang lOOQ va tu dien c6 d u n g khang 200Q. Biet dien ap tuc

X (lOoVs + i.lOO) =

Vi

-

= 200(Q) Z-H = r + iZ
^_

=10(Q)

i = 5V2icos

dan

r^^,,i(2^_2^)

[

dan

=COLI

._ u_

Zr

t h o i tren cuon day la
ti

.,.j;f^

(V).

Huong

g o m d i e n t r o t h u a n R = 55Q mac noi tiep v o i tu dien t h i cong sua't tieu thu
= 4cos(1007tt-7t/4) ( A ) .

(V).

D. i = 4cos(1007it - 7C/4) ( A ) va U ^ L J = 100 V 2 ( V ) .

) )

30

V i du 5: D a t dien ap xoay chieu u = 220 ^/2 coslOOTit (V) vao hai d a u d o a n mach

A.i

tren doan mach chua RL2 .

A . i = 2N/2cos(1007it + 7 t / 6 ) ( A ) v a U i^^^ = WO

%/2Z30x(30 + i ( 3 0 - 0 ) )

Trenmanhinh

y/ft

TnmnnrvDVVHKltang

u = iZ = ^ Z
ZL

=.

dan

_ 6 _ x (100 + 1(100-200)) = 100^y2Z
lOOi
^
^

r,

.

12
41


Cty TiyHHMTVDVVnKhang
V^t li LTDH tren k&nh VTV2, t^p 2 - Chu
TTTT
( V ) = > C h o n A.
u = 100N/2COS l O O n t 12 )

Bo trffhicn

thiic

VHn

Bien

V i d u 2 : M o t doan mach xoay chieu gom dien t r a thuan R mac noi tiep h o p kin
X. H o p k i n X hoac la tu dien hoac cuon cam thuan hoac d i e n t r a thuan. Biet

V I d u 10: M o t doan mach xoay chieu no'i tiep A B theo d u n g thu" tir g o m dien
t r o R = 25N/3 il, cuon cam thuan L c6 cam iIchang lOOQ. Diet dien ap tuc t h o i tren doan mach chiia RL c6 bieu

thuc

bieu thiVc d i e n ap giua hai dau doan mach va d o n g dien t r o n g mach Ian

l u o t la: u = 100 72 coslOOnt (V) va i = 4cos(100Tit - TI/4) ( A ) . H o p k i n X la
A. dien t r a thuan 50 Q.

URi, = 90cos(1007Tt + 7T/6) (V) (t do bang giay). Viet bieu t h i i c d i e n ap giira hai

B. cam thuan v o i cam khang Zi, = 25 Q.

dau doan mach.

C. tu dien v o i d u n g k h a n g Zc = 50 Q.

;

» i ,0

cos(l OOKt - 71/3) (V).

A . u = 30

C. u = 30 V3 cos{l OOrtt + TI/6) (V).

B . u = 30 V2 cos(1007it - 7r/3) ( V ) . , '

Z =

z

u = 30N/3COS

'

D. cam thuan v o i cam khang Zi = 50 Q.

Huang dan

D. u = 30 V2 cos(l OOrtt + 7r/6) (V).

Huong dan
u =iZ =

VIft

R = 25(Q)

Z = R + i(Z, - Z c ) = ^ = ^
= 25 + 25i
, '
4Z-^

90Z'
71
^ - 2 — X (25 73 + i (75 - 1 0 0 ) ) = 3 0 7 3 Z -—
2 5 7 3 + 75i y
^
3

Z L - Zc

• Chon B.

=25(Q)

v i d u 3: M o t doan mach chiVa hai t r o n g ba phan t u : tu dien, dien t r o thuan,
cuon cam thuan mac no'i tiep. Biet dien ap giua hai dau doan mach va

1 0 0 7 l t - - ( V ) = : > C h o n A.

c u o n g d o d o n g dien qua no Ian l u g t c6 bieu thuc: u = 60cos(1007tt - 7t/2) (V),

3,

i = 2sin(100Kt + 7r/6) ( A ) . H o i t r o n g doan mach c6 cac phan t u nao? Ti'nh
2 ) I J n g d u n g de t i m h o p k i n k h i cho b i e t b i e u t h i i c d o n g d i e n hoac d i e n ap.

d u n g khang, cam khang hoac dien tro t u o n g u n g v a i m o i p h a n t u do. T i n h

+

B A M ^ 0 D E [ § ] (De cai dat t i n h toan v o i so p h i i c )

cong suat tieu t h u ciia doan mach.

*

N e u cho bieu thCrc d o n g dienva dien ap giita hai dau doan mach
U = U()

cos

( O t + Cp^i )

i = I() C O s ( 0 ) t + cpi )

thi CO the t i m t r o khang: Z = R + i ( Z L

2

\

"u _

.if:

My

A. R = 1573

Q;Zi, = 1 5 Q v a P = 30(W).

B. R = 15 Q; Zc = 15 73 Q va P = 30 73 (W).

i - : ' ' ' . ' JX

C . R = 15 73 Q ; Z c = 1 5 Q v a P = 3073 (W).
D . R = 15 Q ; Z I , = 1573

UQ^^U

u = 2 4 0 7 2 c o s l 0 0 T i t ( V ) v a i = 472cos(1007it-7T/6)(A).
:j,

C. 150 Q va l/{3n) m F .

D . 30V3 Q va 1/(3TT) mF.

Z = R + i(ZL-Zc) = - =

Huang dan
I'

= 3073 + 30i. Tir do suy ra: R = 3073(n) va
6

60 - Zc = 3 0 ( f i ) =^ Zc = 30(Q) => C = (oC

^ = 1573-151

2Z-

>^5i I' alt I't j 5 » t / i '

R = 1573(Q)
Z L - Z C

= -15(Q):

Z c - 1 5 ( Q ) =i> P = I ^ R = 3 0 7 3 ( W )

Chon B .

Z L = 0

V i d u 4 : D a t vao 2 dau hop k i n X (chi g o m cac phan t u mac n o i tiep) m o t dien

Zj^ = ( D L = 60Q=>Z = R + i ( Z , - Z c ) = R + i ( 6 0 - Z c )

^

\^^:"^^>r''

60Z-

f >!

B. 75 Q va I/TT mF.

-

' j'

Viet lai bieu thuc: i = 2sin(1007it + it/6) (A) = 2cos(1007it - 7r/3) ( A ) .

'

A . 30 Q va l/(3n) m F .

,,

,,„

Huong dan

gii>a hai dau doan mcich va d o n g dien trong mach Ian l u g t la:

^^^^

;
'

Q va P = 30 ( W ) .

0,6/K ( H ) , d i e n t r a t h u a n R va tu d i e n c6 dien d u n g C. Biet bieu thiic d i e n ap

M a t k h a c : Z = -=

,

i, : , ;

Vi d u 1: M o t doan mach xoay chieu no'i tiep g o m cuon cam t h u a n c6 d o t u cam

Gia t r i cua R va C Ian l u g t la

, •>

10 -3 • (F)
3n

,,,
=>ChonD.

ap

xoay

chieu

u = 1 0 0 c o s ( 1 0 0 K t + TI/6)

i = 2 c o s ( 1 0 0 7 i t + 271/3) ( A ) .
thuc u =
i = 5 72

400-72

(V)

thi

cuong

do

d o n g d i e n qua mach

N e u thay dien ap tren bang d i e n ap khac c6

c o s ( 2 0 0 7 r t + 7i/3)

(V)

thi

cuong

dg

bieu

dong dien:

c o s ( 2 0 0 7 r t - 7i/6) ( A ) . X c6 t h e c h i i a

A . R = 2 5 ( Q ) , L = 2 , 5 / 7 i ( H ) , C = 10-*/7t ( F ) .
B . L = 0,7/71 ( H ) , C = 10-3/(1271) ( F ) .
'

43


Bo trp hien tiluc

C. L =

1,5/7T

D. R = 2

5

V^l li L TP 11 tren kcnh

VTV2. t4p2-Chu

V0n

Cty TlSnn MTV D VVH Khang

Blin

Huong

(H), C = l,5.10"V7t (F).

(Q),

L = 5 / 1 2 7 1 (H).

•^"'•'f! n v * y !

st.o:' >,

20o72z^''
. ^ UAM ^ ^
ZAM

lOOZ"
R = 0
Z =R +i (ZL - Zc) =- =
= - 5 0 i =>

, 2^
71
'
2Z

^

TSMi!'.4.', A,

2ZL

Z.^

u/"°^-^3

= 80i:

Z,

=70(Q)

0,7

L =
IOOT:

= 80

Zc =120(Q)

r-u

T3

•

c = —.IO^VF)

•••"^

-.'>

cuon day la:

B.25a

' '

C. 50 Q.
Huong

i,?,'

, •,;>;.v/i^v

B. Dien ap giua hai dau doan mcich A B tre pha TI:/6 SO v o i dien ap giija hai

„.

d o n g d i e n qua mach c6 dang i = 2cos(100Trt - 7r/3) (A). D i e n t r o thuan cua

Q.

•^

A. C u o n day CO dien t r o r khac 0.

•

V i d y 5: D i e n ap a 2 dau cuon day c6 dang u = lOOcoslOOTit (V) va cirong d o

72

« / v n ' i - ) i o r t .(•/,

K e U u a n nao k h o n g dung?

12%

A.25

• H.nLuri;:

Chon A. ' ' l u i ' r I t ' i (Si ' (
'
«.
' i , . , (, ,

U K = 120cosl007rt (V) va u^^ = 120cos(100Tct + K/3) (V).

(H)

7t

^

r = 125(Q)

Biet dien ap giua hai dau dien tro va hai dau cuon day Ian l u g t la

2Z,

.

»P

V i d u 7: M o t doan mach A B gom dien t r o R mac noi tiep v o i cuon day.

xi' • i\'-A<"\\ ,Ci

6

f

,'=>r,.v.

^ ? r ^ ( 5 0 - 5 0 i ) = 125 + i.216,506

=

"AM

M

R =0

i "572^-^^

^ ZMB = - ^ Z A M

ZMB

7,
Z,. = 2 1 6 , 5 0 6 ^ L = ^ ^ 0 , 6 8 9 ( H )

3"

Z =R+

dan

||j

,5; / " i s .r.->v:

Vl^t

D.125Q.

j>,^ ,,•,;3

dau cuon day.

"

: • .'v . : ,

C. D i ^ n ap h i ^ u d u n g giCta hai dau doan mach A B la 60 7 3 .
^ ^
r• i -itvA '.I r •
D. Fie so cong suat cua doan mach A B bang 0,5 V3 .
^
•
„ .
( i f frH/U:!"inf>d u ' i
Huong dan
Dien ap hai dau doan mach: u^^,, = u,^ +

= 120 + 120Z— = 12073Z —=> Chon C.
3

dan

6

V i d u 8: M a c h dien ap xoay chieu A B no'i tiep chi gom cac phan ti'r n h u dien tro
thuan, cuon cam va t u dien. Doan mach A B g o m hai doan mach A M va M B
Cach 1;

• R = Zcoscp = 25(Q) => C h o n B.

I

mac noi tiep. Doan A M g o m dien tro thuan 50 il mac noi tiep v o i tu dien c6
d u n g khang 50 Q. Biet bieu thuc diC^n ap tren doan A M va tren doan M B Ian

72

l u g t la: UAM = 80cos(100nt - n/4) (V) va u.vm = 200 72

Cach 2: Z = - = — ^ = 25 + 43,3i ^ R = 25(Q)
1
2Z-60
^ '

T i n h tong tro cua doan M B va d o lech pha cua dien ap tren M B so v o i d o n g
.i. I
dien.
,
A. 250 Q va TC/4.

Chu y: Mach

dien dp xony chicu A B gom hai doan mach AM (dd bict) va MB (chua

biet) mac noi dep. Dexdc

cos(1007it + TT/4) (V).

dink MB ta dim vdo: Z ^ B =

i

C. 125 72

tiep. Doan A M g o m dien t r o thuan R = 50 Q mac n o i tiep v o i tu dien c6
d u n g k h a n g 50 Q, doan M B la cuon day c6 dien t r o thuan r va c6 d p tir cam
L. Biet bieu thiVc dien ap tren doan A M va tren doan M B Ian l u g t la:

UAM = SOcoslOOTit (V) va UMD = 200 72 cos(1007Tt + 77T/12) (V). Gia tri cua r va

"

p;:' •

B. 250 Q va - TT/4.

20072Z
i =^
ZAM

QOS

D. 125 72 Q va TT/2.

Humtgd^n

=
xZ ^ M " A M

V i d u 6: M a c h d i e n ap xoay chieu A B g o m hai doan mach A M va M B mac n o i

"

Qva-7T/2.

^''•Vfmlq.-vV

_

=^
^ Z „ B =^
ZAM =
^ ( 5 0 - 50i) = 250Z ^
^Mb
"AM
80Z4

ZM[5-250(Q)
%
=>ChonA. (Sau k h i nhap vao may tinh
V M B = -

. ^^ ;
'••

200^Z'^
^(5O-50i)
80Z-^

cam k h a n g Z L Ian lu-gt la

A. 1 2 5 Q v a O , 6 9 H .

B. 75 Q va 0,69 H .

C. 125 Q va 1,38 H .

D. 176,8 Q v a 0,976 H .

neu bam p h i m '=' t h i duoc ket qua 176,77669 + 176,77669i, con neu b a m
'shift 2 3 = ' t h i dixgc ket qua 250).

AV,,
45


Bd

trphJSn thitc V$t

tren

IILTDH

henli

VTV2.

t^p

-

2

Cty TISmi MTV D VVtl Khang
Chu

Van

Bien

Huong

V i d u 9: Dat vao hai dau A B mot d i e n ap xony chicu co gia trj hieu d u n g va tan
so k h o n g d o i . Doan mach A B g o m doan mach A M noi tiep v o i doan mach
M B . Doan mach A M g o m cuon cam thuan co cam khang 50 (Q) va dien tro

\
_UAR

va dien t r a thuan R2 mac noi tiep. Dien ap tuc t h o i 6 hai dau doan mach

k h a n g bao nhieu? T i n h tong t r a cua doan mach A B . T i n h d o lech pha cua
d i e n ap tren A B so v o i d o n g dien. T i n h he so cong suat cua mach A B .
Huong

';yniil,.
'0

ZAB

-

+ " M B

V

A M

-

1 +•

" A M

ni.rlii

-'MB
' A M

1 +

' A M

-

'

' ' • '-

• '

^"'lOOZ-^^
12
1+71

J

(!

}-i»>i

-

5072Z

Thuc hien cac thao tac bam may tinh [=] bllilil dJ

x(40-40i)

-7K
12'

J

d u o c ket qua

EE cos

0,84 nghia la coscp « 0,84 => Chon B .
doan mach X. Dat vao 2 dau mach m o t dien ap u = 120N/2 cosl007:t (V) t h i

c u o n g do d o n g dien qua cuon day la i = 0,6 V2 cos(1007:t - 71/6) ( A ) . T i m hieu

(50 + 5 0 i ) .

dien ap hieu d u n g giua 2 dau doan mach X.
A . 2 4 0 V.

200Z-

B.120N/3V.

C.60^/2V.

D.120V.

Huong dim
ux = u - U L = u - I . Z L = 120>y2 - ( 0 , 6 V 2 Z ~ 30)200i = 120^y2Z - 60

N e l l b a m p h i m ' = ' ta d u o c ki^'t qua: 67,68 + 19,381.
RAB=

- A M

- A M

Sau k h i nhap vao m a y t i n h so'lieu n h u tren:
Tir ket qua nay ta suy ra:

150

I^MB

V i du 11: C u o n day t h u a n cam co he so t u cam L = 2/71 (H) mac n o i tiep v o i

dan

T o n g tro p h u c toan mach:
" A M

( " A M + ^ M B ) .

" A M

A M va M B Ian l u g t la UA.\ = 200cos(100Tit + TI/6) (V) va UMH = 100cos(1007Tt 57T/12) ( V ) . H o i tren A B tong cam khang nhieu h o n hay it h o n tong d u n g

dan

= 40(Q)

Zr =

thuan R i = 50 (Q) mac noi tiep. Doan mach N B g o m tu dien co dien d u n g C

67,68Q va Z , ( ^ B ) "

ZC(AB)=

19,38Q (tong

r:>Ux = 1 2 0 ( V ) = ^ C h o n D .

cam khang nhieu h o n tong d u n g khang la 19,38 Q).

Z^B

= 70,4Q va

cpAi?

= 0,279 rad (Dien ap UAB som

pha h o n i la 0,279 rad).

Phuangphdpgidi

He so cong suat cua mach A B : coscpAu = cos0,279 = 0,96.

'"'

Co the t i n h true tiep coscpAis bang may t i n h casio fx570es t u ket qua:
12

1+

(50 + 50i)

^ ^

1) D i e u kien cong h u a n g
Z , . Z c « L o . ~ « c o =^

f

=

VLC

271

O T

= 27IVLC

I»U

coC
2

Bam p h i m ' = '

21='

o

Z z , = I Z c o S L c . = S-i

200Z ^6
Bam 'shift

1

BAi TOAN LIEN QUAN DEN CQNG Hl/dNG DI^N
VA DIEU KlfN LECH PHA

Neu bam p h i m 'shift 2 3 =' ta d u o c ket qua: 70,4Z0,279.
T u ket qua nay ta suy ra:

Vl^t

--==>p

I
(de lay goc

'iii.ix -

,

=r-

'cong_luH)ng

'max

R = —

*

t''«'

R

H e qua cua hien t u o n g :

cpAis)

Bam 'cos =' se d u o c ket qua 0,96 (tuc la cos(pAB= 0,96).

tan cp = 0 =>(p = 0 ne n u = U R , i : cung pha :

V i du 10: (DH-2011) Doan mach A B g o m hai doan mach A M va M B mac n o i

•

tiep. Doan mach A M g o m dien t r o thuan R i = 40 Q mac noi tiep v o i tu dien

V i du 1: Cho d o a n mach R L C n o i tiep co gia t r i cac p h a n t u co d i n h . Dat vao

CO dien d u n g C = 0,25/:: mF, doan mach M B g o m d i e n t r o t h u a n R2 mac noi

hai d a u doan mach nay m o t hieu dien the xoay chieu co tan so thay d o i . K h i

tiep v o i cuon cam thuan. Dat vao A , B dien ap xoay chieu co gia t r i hieu

tan so goc cua d o n g d i e n bang COQ t h i cam khang va d u n g k h a n g co gia t r i 20

d u n g va tan so k h o n g d o i t h i dien ap tuc thoi 6 hai dau doan mach A M va

Q va 80 Q. De t r o n g mach xay ra cong h u o n g , phai thay d o i tan so goc cua

M B Ian l u o t la : UAM = 50 V2 COS(1 OOnt - 7Tr/l 2) V va UMB = ISOcoslOOnt (V).

d o n g d i e n den gia t r i CO bang

H e so cong suat cua doan mach A B la

A.

A. 0,86.

B.0,84.

0.0,95.

D . 0,71.

2 COg

.

B . 0,25

COQ .

C. 0,5

COQ.

D . 4coo.

thUc V$t It LTDII

trphtSn

Ht'ni hcnh

C t r Tiyilll MTV D VVn

VTV2, t^p 2 - Chu VMii isk-ri

Huong dan
Z[

=W(,L

(i)C

= 20(a)

j^hi f = 2 f, t h i Z L 2 = 2 Z L ,

20

L=

-

>Z|,
^50- + 2,25.Zr, =•

hay V - •
• •
0,8

= 80(Q)=>C =

=- ^

vaZ,=VR^.(Z,,-Zc,)^=^
Chon A.

=25(Q)

1

1

I

/20

,v.

'y.

,„

tiep v o i tu dien c6 dien d u n g SOO/TI ().iF). Dat vao hai dau doan mach mot
dien ap xoay chieu tan so 50 (Hz). De d o n g dien t r o n g mach cung pha v o i
dien ap ta phai ghep noi tiep v o i tu C m o t tu C i c6 d i e n d u n g la bao nhieu?

B. 250/Tt (laF).

doan mach M B g o m dien tro thuan R2 mac no'i tiep v o i cuon cam thuan c6 do
tu cam L. Dat dien ap xoay chieu u = Uocoscat (Uo va co k h o n g doi) vao hai

V i d u 2: M o t cuon day c6 dien t r o thuan 100 (Q) va c6 d o t u cam l/n ( H ) , noi

C. 125/7t (^iF).

dau doan mach A B t h i cong sua't tieu thu cua doan mach A B la 85 W . K h i do
LCCO^ = 1 va do lech pha giira UAM va UMB la 90". N e u dat dien ap tren vao hai
dau doan mach M B thi doan mach nay tieu thu cong sua't bang:
C

B. 135 W .

D . 50/7t (^iF).

, = Z, => — +

c. n o w .

A/

U)

= coL => C, = — ( i - i F ) => Chon C.

va bien t r o R mac noi tiep. K h i dat vao hai dau mach m o t dien ap xoay

Z,,=Zc=^P =
Dat dien ap vao A B :

chieu on d j n h c6 tan so'f thi thay An^i'^hC = 1 . K h i thay d o i R t h i

^,
:i

, , ,

,

,

Tir dieu kien 4 T I ^ F L C = 1 suy ra Z L =ZQ,

P' =

R2 =

U'R.
R; +

Hu6iig dan
tuc la t r o n g mach xay ra cong

<

=-1

-Zc

ZL

= - 1 ^ Z L =RiR2

zi

U-R,
R2 + R , R 2

Ri + R2

= P = 8 5 ( W ) = ^ C h o n A.

A

day. Dat vao hai dau doan mach mot dien ap u = U V2 coscot (V) t h i d i e n ap
hai dau t u d i e n C la u ^ = U N/2 cos(a)t - 7t/3) ( V ) . T y so gii>a d u n g k h a n g va
• Chon C.

P thay doi

uc. Mat khdc ui. sani han i la KI2 va uc tre han i la TT/I ; tie do suy ra (p.
V i d u 6: M o t mach d i e n xoay chieu g o m m o t t u d i e n C n o i tiep v o i m o t cuon

^7
I -y
Z = 7 R ' + ( Z | - Z e f = R => Z thay doi

cam k h a n g bang

A. 1/3.

R

B. 1/2.

R = 50Q. K h i xay ra cong h u o n g d tan so'fi t h i c u o n g do d o n g d i f n bang 1 A .

V i I l u o n luon som han

mach la 0,8 A . C a m k h a n g cua cuon day khi con 6 tan so f i la
C. 37,5 Q.

D . 75 Q.
-

la n/2 va theo bai ra U s o m h a n UQ la n/3 nen

^ tre pha h a n I la 71/6, tuc la

(p = - — .

6

C h i tang tan so cua mach dien len gap doi t h i c u o n g do hieu d u n g t r o n g

K h i f = f, t h i Z c , = Z L J va U = U K = I j R = 50 ( V ) .

D.2. x^^^^m

Huang dan

V i d\ 4: D o a n mach xoay chieu RLC mac noi tiep, d i e n t r o thuan cua mach

Huo^tg dan

-•

C. 1.

cos(p = —• = 1 = khong doi VR

48

-(Ijf

Chu y: Neii cho bicii thuc u, ui. hoac uc ta dnh dime do lech pha cua u vai UL hoac

'U,^ = U = khong doi VR

B.50Q.

v > J III

Dat dien ap vao M B :

D. he so cong suat tren mach thay d o i .

A.25Q.

,

,

C. cong suat tieu t h u tren mach thay d o i .

R

'

1

R, + R 2

t a n t p A M tancp^B

B. tong t r o cua mach van k h o n g d o i .

P=-

,

Huong dan

V i d u 3: Cho doan mach d i e n xoay chieu g o m cuon day t h u a n cam L, tu dien C

A . dien ap hieu d u n g gii>a hai dau bien tro thay d o i .

^n^,

A.85W.

D. 170 W .

h i r a n g va l i i c nay :

«• -,1 ,),v'.
mach A M g o m dien t r o thuan R i mac noi tiep v o i tu dien c6 dien d u n g C ,

•Chon A.

• = 2cUn

I w,) 80o)()

De (p = 0 thi Zc +

Vi^t

V i d u 5: ^^9* doan mach A B g o m hai doan mach A M va M B mac noi tiep. Doan

80Wn

De xay ra cong h u a n g : w =

A. 500/K (|,iF).

7

Khang

D o d o :tan(p =

Z,

- Z
^=tan—=>R
R
6

= (Z,--ZL)>/3>0.
V e
L/

D u a vao bieu thuc u va uc suy ra: U A B =

4R ^ + ( Z L

-Zcf

=Zc

^AB =

^^Y

= > 2 ( Z c - Z L ) = Zc=>Zc=2ZL=>ChonD.

49