. S, . F S ,
F = ò BdScosa, (3.3.16)
B , a dS, .
a
dS
S, , , , , (3.3.16)
F = ò BdScosa = BScosa, (3.3.17)
S = pR 2, R,
S = 2, .
: F S, , :
. (3.3.18)
F :
1. S , .
2. a dS, ( , ).
3. .
, I , , . :
F = L×I. (3.3.19)
L .
,
, (3.3.20)
.
(3.3.18) (3.3.20) , , . .
28.
= 1
a = 30 . t = 2, = D = 1 , t = 1,
B (t) = A (t / t) + D (t / t)4.
: = 1 = 0,01 .
a = 30,
= D = 1 ,
t = 1,
t = 2,
B (t) = A (t / t) + D (t / t)4.
: ½ ½.
. ( (3.3.17) (3.3.18)):
F = ò BdScosa = BScosa,
.
, :
S = 2.
(3.3.18) , , :
= [ A (t / t) + D (t / t)4] Scosa = ( / t + 4 Dt 3/ t 4) Scosa =
= ( / t + 4 Dt 3/ t 4) a 2 cosa = 2,86×103 .
: 2,86×103 .
. , a , :
|
|
b
a
(3.3.16)(3.3.17) a , , , (3.3.16)(3.3.17) b = 90 a.
29.
L = 1 ,
I (t) = B (t / t)2. , 2 , = 1, t = 1.
: I (t) = B (t / t)2,
= 2 ,
= 1,
t = 1,
L = 1 ,
: t.
. t (3.3.20):
.
, (3.3.20) . (3.3.20) , :
[ L (B (t / t)2)] = 2 LBt/t 2,
t:
t = (½ ½ t 2)/(2 LB) = 1 .
: 1 .
, (). :
q = q 0 cos (w 0 t + a 0), (3.3.21)
q 0 , w 0 , a 0 .
w 0
w 0 = , (3.3.22)
L , .
( ) R, L, , :
q = q 0 exp (bt) cos (wt + a 0). (3.3.23)
w ,
w = , (3.3.24)
b ,
b = . (3.3.25)
Z , ( ), :
Z = . (3.3.26)
, ,
= 1/ n = 2 p / w 0. (3.3.27)
= 2 p / w, (3.3.28)
w (3.3.24).
30. , R = 4,3×103 , L = 65, n = 20 .
: R = 4,3×103 ,
L = 65 = 65×106 ,
n = 20 = 20×106 .
: b, .
. , . . (3.3.25):
b = ,
: b = = 33×106 1.
(3.3.22) (3.3.24):
|
|
w 0 = , w = .
w , , n :
w =2 pn, (3.3.29)
2 pn = w = .
(3.3.24) w 0, :
w 0 = = , = = 3×1012 .
: 33×106 1; 3×1012 .
31. , , 10000 . , 300 .
: w = 300 = 300000,
1 = 2 = = 10000 = 108 .
: L.
. (3.3.22):
w = ,
:
L = 1/(C w 2).
C , (2.3.34):
1 /C = 1/ 1 + 1/ 2, C = 1 2/( 1 + 2) = /2 = 5×109 .
:
L = 1/(C w ) = 2/(Cw 2) = 2,2×103 .
: 5×109 ; 2,2×103 .
, , .
.
.
N t N0 , :
(t) = N (t)/ N 0. (3.3.20)