, , ,
(12.1)
, , .
:
= f1(x, , z); = f2(, , z); Ez = f3(x, , z), (12.2)
, Ez , . , .
, , , , .
, q 1--2 (. 12.1). , [. (12.1)]:
(12.3)
dl ; El . , ( ) , . , , .
q 1--2--1 (. 12.1). , , , , , , . :
(12.4)
, q, , :
( ) ( )
(12.4)
(12.5)
(12.5) , , , .
Dj, U.
, , :
(12.6)
j1 j2 1 2 , U12 . , (12.6).
. , - . , , , , ( ), . .
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, e (. 12.2). 1 2 r1 r2 Q. (12.6) 1 2, , ( ) l = E = Q/(4pe e0r2) dr = dl:
(12.7)
e0 8,85 10 12 / 1.
(1 e0 , ).
, : j2 0 r2 ¥. (12.7)
(12.8)
, (12.8), .
( ). , . . 12.3 ( ) () .
j = f(x, , ), (12.9)
, , (12.8). , , . (12.6)
(12.10)
- : j2, j1.
j. , 2 1 , (12.10)
(12.11)
dj/d l dj d l l; l .
(12.11) . 12.4. 0 , l1, l 2 l 3. : çdj/d l1 ç, çdj/d l2 ç, çdj/d l3 ç. , , , ; (12.11) , - . , :
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(12.12)
, ,
(12.13)
, . , , (12.6) , l,
(12.14)
(12.11) (12.9), :
(12.15)
(12.16)
N , , ( ):
(12.17)
, , :
(12.18)
, . , j.
() , , , ( ).
(. 12.5) ( ) , l, :
(12.19)
-. (. 12.6).
, , . ,
= qElsin a = pEsin a, (12.20)
. (12.21)
, , , .
. , (. 12.7).
+ _ ( . 12.7 - > +).
F = F_ - F+ = qE_ - qE+ = q(E_ - +). (12.22)
(_ - +)/l, , . ,
(_ - E+)/l = dE/dx, (12.23)
dE/dx , . (12.23),
(12.22)
(12.24)
, , dE/dx. , . , .
, , . (12.18) , , , , (. 12.8):
(12.25)
, l << r, l << r1, r r1,
(12.26)
a (. 12.8). (12.26), (12.25)
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(12.27)
(12.27).
, , (. 12.9), . (12.27), , ( a a . 12.9):
(12.28)
a, Ð AOB = b, a = a + b/2 + +p/2, a = a - b/2 + p/2.
, :
(12.29)
(12.29) (12.28),
(12.30)
(12.30), , ( e r), , (. 12.10), cos a , (. 12.11). , (12.27).
, , ABC (. 12.12). (12.30) , :
UAB: UBC: UCA = pAB: pBC: pCA (12.31)