, , U = Blv sin a,
l - ; a - .
, , : , R - .
12. L = / I.
L = mm0 n 2 lS,
n - ; l , S .
13. ...
14. , R L:
) - , e -... ; t - , ;
) - , I 0 - t = 0; t - , .
15. W =
( )
w = BH /2 = B 2/(2mm0) = mm0 H 2/2.
4.1.
1. l = 80 I = 50 . , , r 0 = 30 .
.
--
(1)
:
, (2)
l , , , , - ; m 0 - ; m - , ( m = 1). , (1), (2) :
, ,
a - . ,
. (3)
dl d a: dl = rd a/sina.
r a (r = r 0/sina), : . , (2) , a1 a2 - .
:
(4)
cos a2 = -cos a1. (4)
. (5)
.2
cosa1 (5),
. (6)
(6), = 26,7 .
2. D , I = 60 , d = 10 . , . (. .), r 1 = 5 , r 2 = 12 .
.
: = 1+ 2.
. 3
, (1)
a - 1 2.
|
|
1 2 I r 1 r 2
1 = m0 I /(2p r 1); B 2 = m0 I /(2p r 2).
1 2 (1),
. (2)
cos a (Ð a = Ð DAC ), d2 = r 12 + r 22 - 2 r 1 r2 cos a,
d - .
(2) :
= 308 .
3. R = 10 I = 80 . , r = 20 .
.
--:
,
d - , I , - .
- (. 4). d .
, : , dl .
d :
d ^ d ||, .. . ,
. 4
, dl , , dB ^ = dB cos b dB = ( , sin a = 1). , , cosb = R / r (. 4). : .
:
.
4. I = 50 a = (2/3)p.. (. . 5). d = 5 .
. 5
. 5
.
, (. 5) 1 2 , 1 2, .. = 1 + 2.
2 . --, , , d = 0, .. [ d ]= 0.
B 1 , (4), 1: r 0 - 1 (. . 5)
a 10 ( ), a 2 = a = 2 p /3. r 0 = d sin(p - a). .
B =B 1 (B 2 = 0), .
1 . . 5 ( , ).
:
5. (. . 6) I 1 = 80 A I 2 = 60 A. d 10 . , .
.
, I 1 I 2,
. 6
= 1 + 2, 1 - , I 1; 2 - , I 2 ( - ).
|
|
1 2, , , . (. . 6)
,
1 2 :
.
r 0 = d /2. .
: .
6. , .7. R 10 . , I = 80 , .
.
, : .
. 7
(. 7): (1 3), , (2) R. , , - , , .
1, = 0 = + . , , : = 2 + 3.
2 , : .
, .
3 , (4), 1: .
r 0 = R, a1 = p/2 (cos a1 = 0), a 2 p (cos a2 = -1). .
, = 2 + 3 = + ,
.
:
7. l = 2 , d = 20 , I = 1 . .
.
, , . , .
, ( I 1 I 2) . I 1 ( I 2) , . 1
. (1)
, . , dF = I 2 B 1 dl. 1, .
F :
.
, I 1= I 2 = I,
.
:
. 8
d , d .
8. , U = 600 , = 0,3 . R .
.
, : . , . 9
() n.
,
, (1)
m - . . 9 () . ( n .). , ( ).
(1) ( ):
|
|
F = ma n. (2)
F = qvB sin a. sin a = 1, F = qvB. a n = v 2/ R, (2) : qvB = m v 2/ R. :
R = mv / (qB). (3)
, , .. = D W, q (j 1 - j 2) = W 2 - W 1, (j1 - j2) = U - ( ); W 1 W 2 - .
W 1 0, , , W = mv 2/2, qU = mv 2/2.
(3),
(4)
:
9. , ( = 0,2 ), R = 5 . m .
.
, .
, : - ; - .
, = (2 pR)/ v.
(1)