TỪ TRƯỜNG CỦA DÒNG ĐIỆN KHÔNG ĐỔI ppt

TỪ TRƯỜNG CỦA DÒNG ĐIỆN
KHÔNG ĐỔI

I. TỪ TRƯỜNG & TƯƠNG TÁC TỪ

 !"#$
%&'()
*((+ !"#,
-.$%&
/((0'12((,
3-$)
*4567.$"#89(
$%&:;<)
















I. TỪ TRƯỜNG & TƯƠNG TÁC TỪ

=.$6#/#2>?21@9(
%&A1<+(&1B" #0>"#
51B #$51B#?#9(
%&12)
C#2D(EFGH 24"IBJ(9K/1LM1M 
12(&7N.7#2O ?'B-11@ ("
7#7P"(&9+Q)
JQER #4"IS(-T1M?,?(-11@
22UQ+,A
V6' AW
06#AX(&12)
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




I. TỪ TRƯỜNG & TƯƠNG TÁC TỪ
T TRƯNG:
Y51B"#94Z9<+9
(%&#["5"O9
(%&12)
Tnh cht cơ bn:
/[""O9($%& 
X"5"O9(\O
]XZ9<+9($%
&
Y51B0U17@(&9"0M
#0I"#CM.(\5

B


I. ĐỊNH LUẬT BIOT - SAVART
E) C^/Y_`Ka*Ybcd*=Je*
/>f9+#6>;-" 
gI0>"#M-Qh
/-#6"#-#6if 1Pf"
G)`KjYkflmJn*K]moY
CM<PP1$%(pqM-Qh
q"-[&P rf
lId

r
r
lId
kBd



3
=
r

π
µ
4
0
=k
θ

r
M
I
I
r
0
2
4
Idl r
dB
r
µ
π
×
=
r
r
r
( )
m
H
7
0
10.4
−
=
πµ



I. ĐỊNH LUẬT BIOT - SAVART
lId

θ
r

Bd


 !"#
Bd

lId

2
0
4
sin
r
Idl
Bd
π
θµ
=

$%&'(") " *+,(-./012
%&'3*4563708937:
;
%:%<1%= 
0

2
4
Idl r
B dB
r
µ
π
×
= =
∫ ∫
r
r
r r
%*/01&>#%:*3137?=@A
5= 
;
 *B C$1:+)D37:
;
!E-.
B C$(>0= +,(4-.B C$1%+)437
:
;
%:#<A
1 2 3

n i
B B B B B B= + + + + =
∑
ur uur uur uur uur uur
F

G
H

I. ĐỊNH LUẬT BIOT - SAVART
3ICG/-.B C$2 "37?.B
ACảm ứng từ của dòng điện thẳng
J*37?=@313KL!E =
=D#DM237?"#

r


Bd

lId


α

α

α
θ
N
O

O


P

2
0
4
sin
r
Idl
dB
π
θµ
=
αα
π
µ
d
h
I
dB cos
4
0
=
α
α
α
2
cos
;
cos
hd
dl
h

r ==
( )
12
00
sinsin
2
cos
2
2
1
2
1
21
αα
π
µ
αα
π
µ
α
α
−===
∫∫
h
I
d
h
I
dBB
A

A
AA
( )
12
0
sinsin
2
21
αα
π
µ
−=
h
I
B
AA
h
I
B
AA
π
µ
2
0
21
=
2
&
2
21

π
α
π
α
=−=
B

B

0C37?
Bd

Q
R
S
T


I. ĐỊNH LUẬT BIOT - SAVART
ACảm ứng từ của dòng điện tròn bán kính R
U πV

-..W040523?/0L=+)37?%7
=1 37?%7
2
0
4 r
Idl
dB
π

µ
=
r


Bd

lId


β
3X
Y
α
V
N

Y

Z
B

zzyyxx
edBedBedBBd


++=
∫∫∫ ∫
++==
dd

zz
dd
yy
dd dd
xx
dBedBedBeBdB


( )
23
22
0
2 hR
IS
eB
z
+
=
π
µ

nISp
m

=
m
p

z
en


=
( )
m
p
hR
B


23
22
0
2 +
=
π
µ
mzzzO
p
R
e
R
IS
e
R
I
eB


3
0

3
00
22
2
π
µ
π
µµ
===
n

ISp
m
=


F
G
H
Q

III. ĐƯỜNG SỨC CẢM ỨNG TỪ
[ BEB2$%&'!&'&%\4? &']C$%&'A
[&']CB C$#^&'*_%*$%&']**505=
` 2%I0&.2-.B C$= A
JD#D2-.B C$
6&']C@ ".W3?/&']CB C$+,
"#2-.B C$= A
B


n
dS
dN
B =
T

ĐỊNH LÝ GAUSS ĐỐI VỚI TỪ TRƯỜNG
1. Từ Thông :
s3(&(U$r12(&51B7t XqB\i
+r (Ur#$;r2251B1Or
NX%uv51B6)YM2P! Y5X+
r
r

'ir"O(U-wXB\.(\5


c2
Y5X+7&(Ur
*r"#(U$ 1(Ur
JP5X12rfxM7M1yx7z
B

α
cosBdSSdBd
m
==Φ


α

cosdSdS
n
=
nm
BdSd =Φ
∫
=Φ
S
m
SdB


∫
=Φ
S
m
SdB


n

$@34%W
1 a3&.0b"*
D-.0405
n

S
R



ĐỊNH LÝ GAUSS ĐỐI VỚI TỪ TRƯỜNG
2. Định lý Gauss:
s3(&(U$r7t1251B (Ur#G(Ur
E
#r
G
)
Y5X+(U$r

0>1(UruvY5X\B\
.(\1;(Ur#5X(\B\.(\
#2(Ur)2
Y5uv
PHÁT BIỂU:
Y5X+(>(U$
67@X
B

n

∫∫∫
+=
21
21
SSS
SdBSdBSdB







0&0
21
21
<>
∫∫
SS
SdBSdB




∫∫
=
21
21
SS
SdBSdB




0=
∫
S
SdB




3


J






3


1
Sd

2
Sd

B

B


F
G
H

ĐỊNH LÝ GAUSS ĐỐI VỚI TỪ TRƯỜNG

2. Định lý Gauss:
YVX\L11{=%7NX\yG|z
*O
c2"#%$097:(U$r7'O
`1'yG}z"#9-iP"I=q515)
`1'#\;1BM.(\5"#(&1BXZ 
B.(\5X%(<-,X%(4V)
J6#,!"#12OXZ95$92151B
q$9211B(#<i51B"#2
$%&)
B

Q
∫∫
∇=
VS
dvBSdB



.
0. =∇
∫
V
dvB

0. =∇ B


ĐỊNH LÝ AMPÈRE

1. Lưu số của vectơ cm ứng từ:
s3(&B2$y/z12(&51B7t "#.(\59
%(p∈(C)YM2P! 9"0
"#"qiM.(\5>M2B2$y/z125
1B

B


B

ld

J
∫
=
C
ldBL


T
B


ĐỊNH LÝ AMPÈRE
2. Định lý dòng tòan phần:
a. Phát biểu:
]qi3.(\5>M2(&B2$
7'7@N9qB&+$97:B
22 µ

H

b.

Chứng minh:
Y51Biw#X4
s351Biw#X9
Y1B0-B2y/z@(12(U-wy`z
JB2$y/z72+f)
]qiM>M2By/z
Y5'A

S
B

∑
∫
==
i
i
C
IldBL
0
µ


B

c
J

N
3θ
%


α
ld

∫∫
=
CC
dlBldB
α
cos



θα
rddl =cos
∫∫
=
CC
rd
r
I
ldB
θ
π
µ
2

0


∫∫
=
CC
d
I
ldB
θ
π
µ
2
0


R
F

ĐỊNH LÝ AMPÈRE
b.

Chứng minh:
Y51Biw#X4
s351Biw#X9
Y1B0-B2y/z@(12(U-wy`z

JB2$y/z72+f)
*V-$y α~π•Gz!"#6P1OB
2y/zV64iM2+€U'

C4
*0-$y αvπ•Gz!"#6P1OB
2y/z064iM2+€U'
B

ld

0>ldB


IL
0
µ
=
0<ldB


IL
0
µ
−=
ld

B

:
0<ldB


0>ldB



B

B

ld

ld

IldBL
C
0
µ
==
∫


d5&I0/
e5&&>0/
F

ĐỊNH LÝ AMPÈRE

JB2$y/zX72+f)
Y
∫
=
C
ldBL



∫∫
∫∫
+=
+=
0
0

'
θ
θ
ldBldB
ldBldBL
FNEEMF














−+=

θ
π
µ
θ
π
µ
IIL
22
00
'B

ld

B

J
N
θ
f

ld

c


g
F

ĐỊNH LÝ AMPÈRE
7)

Chứng minh:
Y51Biw#X4
s351Biw#X9
Y1B0-B2y/zX@(12(U-wy`z
`$#
Y12@(12(-y`z
@(22
C' O
=>y/•z"#'iy/z"O(-y`z y/•zA72Z(P%;
'i12(-y`z #

S
B

ld

2
ld

1
ld

2
ldB


⊥
1
0
21

ldBldBldBldB









=+=
21
ldldld

+=
ld

IldBldBL
CC
0
'
1

µ
===
∫∫





1
ld

ld

B

J
N

1
ld

c

Jh
2
ld


ĐỊNH LÝ AMPÈRE
7)
Chứng minh:
Y1B0-N+
Y1B0-97' +.1O
]qiM.(\5>M2(&B2y/z$7'1251B 
"N9qB&<O+(U97:B2

"#.(\52f


1
f

vH 6i2f

1V66Piy/z)
f

~H 6i2f

1066Piy/z)
=>"#(4&+(Uyrz
3

n

Sd

J








∑
∫
==

n
i
i
C
IldBL
0
µ


∑
=
n
i
i
BB

i
B

i
B

i
B

j

∫
∑
=

S
n
i
i
SdjI


U
∫∫
=
SC
SdjldB




0
µ
JCS%)
-*B/-.
( )
∫∫
×∇=
SC
SdBldB




.

UM
( )
∫∫
=×∇
CS
SdjSdB




0
.
µ
U+\E=+)J
jH
jB




=×∇
=×∇
0
µ
i=01
2W#j
 0k%-

ĐỊNH LÝ AMPÈRE
C)


Áp dụng định lý dòng tòan phần
g51B$q<\ -[P"I#%‚#<P
M.(\5)
Y51B12&'<
=.h&Z(*f9+)c2$q<\ 9(>%(
1Oy/z(L7$161P7@ --<
y/z 6'A)
Y

Y12 "#q1O
P6#iB1)
ƒ&y1~„
E
>D1v„
G
z51B7@X)
NIrBNIldB
C
00
2
µπµ
=⇒=
∫


r
NI
B
π

µ
2
0
=
r
N
n
π
2
=
InB
0
µ
=
B

B


ĐỊNH LÝ AMPÈRE
C)

Áp dụng định lý dòng tòan phần
Y51B12q1#
…w#X9%<M((&&'<
7$"XV
c2.(\59(>%(7O12q67@#7@
∞≈=
21
RR

InB
0
µ
=

ĐỊNH LUẬT AMPÈRE
s3-Qh#(&;1).(\5
29219P1$i-Qh0<P5P"4k2{
r1
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