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Department of Physics
Department of Physics
Chap. 28Magnetic Fields
철공소의
쇠붙이
분류
작업장
Department of Physics
(28 – 1)
Chapter 28 Magnetic Fields
(자기장)In this chapter we will cover the following topics:
B
Magnetic field vector
Magnetic force (자기력) on a moving charge
Magnetic field lines
Motion of a moving charged particle in a uniform magnetic field
Magnetic force on a current carrying wire
Magnetic torque on a wire loop
Magnetic dipole, magnetic dipole moment (자기쌍극자)
Mass spectroscopy (질량분석기)
p. 922
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ˆˆ ˆ , ˆˆ ˆ , ˆˆ ˆ
x y z
x y z
x y z
a a i a j a k
b b i b j b k
c c i c j c k
c = a bThe Vector Product in terms of Vector Components
Those familiar with the use of determinants can use the expression
x y z
x y z
i j ka b a a a
b b b
Note :
c
cy z x
x y
z x y y
y
x
x
z
z
z
a b a
c a
a b
b a b
a b
b
The order of the two vectors in the cross product
is impor
tan
t
b a a b
Note :
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2) 자기장의 정의
v B´
| |BF q v B= ´
| |BF q v B=- ´
BF qv B= ´ 속도 v 로운동중인전하 q 는
자기장 B 속에서힘 F 를 받음
p. 923
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B
| |BF q v B=- ´
액체수소로 채워진bubble chamber
감마선
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The relation between
the magnetic field lines and are:
B
1. At any point P the magnetic field vector B is tangent to the
Magneti
magneti
c Field Li
c field l
nes :
ines
PPB
magnetic field line
2. The magnitude of the magnetic field vector B is prdensity of the ma
oportional to th gnetic field le ines
magnetic field linesPQ
PB
QB
P QB B
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* form loops* pole: field lines * pole: field lines form a " "
(
North emergeSout
)
h enter
closed
Magnetic dipole자기쌍극자
2. 자기장선
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(p.926)
EF qE
BF qv B
e/m: (specific charge)
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(p.745)
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BF
B
v
BF qv B= ´
(p.931)
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“Magnetic Bottle”
(p.933)
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보기문제 (p.933)
mvrqB
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Cyclotron 가속기
or0 0q q
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(Hall 효과, pp. 928)
p.937
→도선을 오른쪽으로휘게 함
BF qv B= ´
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?B
BdF idL B=
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. dL
B
dF
i
BdF idL B=
BF i dL B
BF qv B= ´
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p.940
1 3
2
4
BdF idL B=
1 32) torque( :
( )( )sin ( )( )sin sin = sin2 2
)F Fb abbiaB iaB i B i BA
힘 과 에 회전력,돌림힘의한
회전력;일반물리학(I)( )
r Ft = ´
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sin
[
|
B=
]
| iA A B
iA B
i B
m
t q
t
= º
´
´ ´º
p.942
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p.746 (22-9절)
전기쌍극자의 퍼텐셜에너지
(복습)
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( ) sin
( = always) 2
[ ]NiA B
A ab
t
p
q
q
kf= º=
검류계의 원리
[ ]sin | |i B iA A Bqt = º ´
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지구의 자기장
지자기 현상의 근원=지구의 자기 쌍극자 모멘트
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Magnetic Fields
Currents
Chapter 29
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p.954
7 64 10 T m/A 1.26 10 T m/A " "( )
o
透磁常투자상수; 數permeability constant
2
ˆ4
oi ds rdBr
실험식
20
1 ˆ4
dqdE rr
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02
sin4 r
i dsdB
긴 직선도선에 흐르는전류에 의한 자기장
2
oiBR
3/ 2 2 2 22 2
dx xa x ax a
2 2sin R R
r s R
02 2 3/2
0 0
0
2 =2 (s +R )
2
i R dsB dB
iR
2
tansec
s R xds R x dx
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0 02 2
sin 90 4 4
i ds i dsdBR R
ds Rd
circle 2 oiB
R
dB
B
2
ˆ4
oi ds rdBr
r
원형 고리전류 중심점의 자기장:
0 02
0 0
4 4
iiR dB dB dR R
0 ; ( )
4iBR
원호의 중심점
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p.959보기문제
1 2 0B B
3 8oB iR
2
ˆ4
oi ds rdBr
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0
0
; 2
sin 902
aa ba b a
a bba b a
iB F i L Bd
Li iF i LBd
평행한 두 직선도선에 흐르는 전류 p.961
확인문제 1, p. 962
도선 a, b, c 중에 가장 센 자기력을 받는 것은?
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p.963
2. Ampere's Law
1 2enci i i
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Bh
oB ni
n= 코일 단위길이당 감긴 도선의 수
oB ni
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Magnetic Field of a Toroid
riNB
iNrB1
2
)2)((
0
0
The magnetic field inside a toroid is not uniform.Note :
토로이드
0 B =외부
( Check it by yoursewhy? lf!)
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20 0
2 2 3/2 2 2 3/2
2 ( ) 2 ( )
i RR z R z
m m mp
pp
= =+ +
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2; Ni AA Rpm= =0
2 2 3/2( )2 ( )
B zR z
mmp
=+
참고:
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