Физика-КР4

4. . -

.

-

( -

, -

).

-

:

	,	(1.13)
S (B dS) 0

. , -

, .

, – (

,

).

b

. :

			0			2	I
	L (B dl ) L Bl	dl						2	b 0	I
			4			b

, , -

L 0 ,

L ( ):

	I
L (B dl ) L Bl dl 0		(1.14)

, , -

, .

( -

)

.

4: ( ) -

I.

	I		l,
			N . -
		D	,
			-
	N		,
			. -
	l

11

. -

:

L (B dl ) B l 0 N I ,

= 0 I N/l. (1.15)

, -

, -

.

, -

, , .

L (1.10)

r, . -

L, . , L (B dl ) B 2 r , –

, .

, -

2 RnI (R – , n- , I – ). B 2 r 0 2 Rn I ,

B 0 nI R . , ,

r

.

5. .

, , , -

. ,

, .

( ). -

/,

0. = / + 0.

,

p m

V

V , (1.16)

m – , V –

” , .

.J

12

,

, :

= 0 – J.	(1.17)
,

J = ,	(1.18)

– , .

(1.17) J (1.18) -

,

= 0(1 + ) 0 ,

(1.19)

= 1 + , -

; 0

. -

:

1), , < 1.

2), , > 1.

3), , >>1.

-

, .

( -

), ( )

) .

, -

, ,

, -

( “ ”

).

L (H dl ) N I

-

:

B 0 H

.

13

-

, - ( ,

) , -

. ( -

	) , -	I	dx
	-
			*
	V .	B
	-		d
		n	V
	, . -
			F

, ( ), ,

, - -

. , -

, , ,

. -. , ,

, , -

, ,

, -

.

, . , -

, , , -

, -

.

(

) ,

.
	( q) E * ( q) [V B] , :
		. -
E * [V B]

L, ,

:

Ei [V B] dl .

L

: Ei V B l ,

l- . -

, ,

, -

.

14

-

-.

( ,

). -

Ei L (E dl ) L ((E E * ) dl ) L (E * dl ) L [V B] dl l [V B] dl

V B l (dx / dt) B l B dS / dt d (B S) / dt / dt

, dl -

( . E*, “ -

”), E . -

,

, -

, ( ):

(E dl ) Ei		/ dt	d (B dS )
L				S
			dt

, -

, .

, ,

, -

.

,

.

, . -

,

. -

, , .

, -

. -

.

,

L I

L .

, -

.

,

, -

15

.

, , ,

.

5. N

l D.

I, -

= 0 I N/l. -

S= ( 0 I N/l) ( D2/4). , -

, = ( 0 N2 D2/(l 4)) I.

L= 0 N2 D2/(l 4)= 0 (N/l)2 V,

V- .

-

. -

W=L I2/2.

:

	L I 2			0	N 2	V I 2		B 2
W									V
					2 l 2
	2							2 0

V- , -

( -

), B2/(2 0) -

. , -

-, w= B2/(2 0), -

, .

, -

“ -

”.

“ ”.

:

		(2.1)
B 0 H

- , 0-

.

:

16

	0		I				0		I sin
dB				d l r		dB				dl	(2.2)
	4		r 3				4		r 2

dB ,

dl I, r- ,

, , - -

r .

, -

:

dB	0 I							(2.3)
					2
	2 R
R- .
:
dB	0			2 R 2 I				(2.4)
			(R 2 h 2 )3/2
	4

h ,

.

, :

dB	0		I	(cos 1 cos	2 )	(2.5)	I		1
	4		b
.1 -									b	B
- , -
.
-									2
						(2.6)
	H n I								.1
n- .
, :
						F I l B sin				(2.7)
		F I l B

l- , - -

.

( -

):
F	0		I1 I2		(2.8)
			l2
	2
l- .
:
					(2.9)
pm I S		n

17

S- , I- , n-

( -

, ).

, , -

:

		B M p m B sin	(2.10)
M pm

- pm .

:

		B p m B cos	(2.11)
	Wn pm

,

( ):

(2.12)

F q E

V B (

E 0 ) F q V B sin

V- , - V .

:

SBn dS

(2.13)

B dS B dS cos Bn dS

- dS.

( ):

(2.14)

N

N- ( ).

(

) :

(2.15)

A I

:

Ei

(2.16)

:

dt

dI

ES

L

(2.17)

dt

:

(2.18)

L 0 n2 V

n- , V- .

:

d

D

n

(2.19)

L H l dl I

S Dn dS S jn

dS

dt

t

:

B

B

n

(2.20)

L El dl

S

dS

dt

t

:

18

	W		L I 2					(2.21)
				2
:
				B 2			0 H 2
w	(B H )							(2.22)
				2 0
2						2

:

Bn1 Bn 2 0 H t1 H t 2 0

(2.23)

“n” “t”

, .

2.2 .

, -

.

: , , -

, .. -

.

, . -

x(t) A cos( 0 t 0 )

(2.24, )

, 0 -

0, =2 / 0.

(t) (2.24, )

	d 2 x(t)	02 x(t) 0	(2.24, )
	dx 2

-

.

, .

1. - m, -

k. ,

x=0 F=- k x, ( ) m a=-k x, x (k/m) x 0 ( -

t: x dx/dt ).

19

(2.24) ,

0 k/m .

2.-

-

L. R. -

I R+Uc=EL, Uc=Q/C,

E L L I L Q .

Q	R	Q	1	Q 0			(2.25)
	L		L C
R=0 -
Q 0			1/			.
					L C

.

-

, -

, , . -

2- , x1=A1 cos( t+ 1), x2=A2 cos( t+ 2), -

. -

(2.24, ). -

	,	Y
	.		A
	A cos . ,
		A2	A1sin 1
	A
			+
	0 ,	2	A2sin 2
		1	A1
	(t)= 0t+ 0. - -		X
	A -	A1cos 1+A2cos 2
	(2.24, ).
	x1 x2		.2

-

( .2). A1 A2 -

0, ( 2- 1) -

. , -

A=A1+A2.

x x1 x 2

A cos( 0 t 0 )

(2.26)

A

1sin

A

2 sin 2

A

A

2

A

2

2A1 A 2 cos(

1 ) tg 0

1

1

2

2

A1cos 1

A

2 cos 2

20