Методическое пособие по физике 2
.pdf3.2.%2) 7 !!" 8 9 / )-& /"0" 2" .)-!1-2 2 )2"$-1-- 2" '.
") -& /-' *-!-* *
3 (1 * 2 &- ( — 2 ( % ' & ( -
&, & ( , " 0# " & + 1 * + -
& & + ' (", ) #@ + " 0 & (:
E = |
F |
. |
(3.2.1) |
|
q0
= ' (" ( '+ * +).
( (, '" )- & & +) ' (" ) q (1 0-
& :
E = k |
q |
er , |
(3.2.2) |
|
|
|
|||
r |
2 |
|||
|
|
|
|
-" er — " & + , + ' (" q " & (
( . 3.4).
A " & '" ( * ) & & +-
) ' (" ), ' * 0# (1 " ( ( $ -
) '$ :
E = Ei , |
(3.2.3) |
i |
|
-" Ei — (1 * (, '" )- i–) & & +) ' (" ) " & (3.2.2), . .
11
E = Ei = |
1 |
|
qi |
er . |
(3.2.4) |
4πε0 |
2 |
||||
i |
i ri |
|
A " & '" ( + "-
+) ' (" ), " ( *' ( $ '$ * B-
) V, ' ) )+ 2 ) ' (" ) ' ( & ) + B )+ dV.
1"+ & ) + B ) dV " 1 & ) + -
& & + ' (" dq. 3 (1 * ( " & & + ( ))-
) (1 , '" )+ 1"+) ) ' (" ):
E = |
|
dE = |
1 |
|
|
dq |
er , |
(3.2.5) |
|
|
4πε |
0 |
r 2 |
||||||
|
|
|
|
||||||
|
|
|
|
|
|
|
|
-" ' (" dq ) 1 + * " & ' * - -
" (:
dq = ρdV , -" ρ – B@) ( * ' (";
, -" σ – ( * ' (";
dq = τ dL , -" τ – ( * ' (".
)-* )+ ) 3 !- $% %&
)-* ) 3. & & + 2 & ' (" q1 = 10–9 q2 = –2·10–9
( . 3.5) "( ( '" ( d = 10 ) "- "- . -
" * (1 * E (, '" )-
2 ) ' (" ) & , " ' (" |
|
|
|
:6 |
|
|
|
|
|
q1 r1 = 9 ) ' (" q2 r2 = 7 ). |
|
|
C |
|
|
|
|
|
|
3 !- . "( ' $ - |
|
6 |
|
: |
|
|
|||
|
|
|
|
|
'$ (3.2.4), & (1 * ( |
|
|
|
:7 |
|
|
|
|
7 |
"+ ( ' (1 ( |
|
|
|
|
|
|
|
|
|
E1, '" )- ' (" ) q1 (- |
6 |
|
|
7 |
1 E2, '" )- ' (" ) q2. |
|
;<:;9 |
|
|
E = E1 + E2 ,
12
-" E1 |
= |
q1 |
|
E2 |
= |
q2 |
|
|
. |
(3.2.6) |
|||
4πε |
0 |
r 2 |
4πε |
0 |
r |
2 |
|||||||
|
|
|
|
|
|
||||||||
|
|
|
1 |
|
|
|
2 |
|
|
& ' * 0#- " ( ( ) #*0 )+ -
:
E = E 2 |
+ E 2 |
+ 2E E cosα , |
(3.2.7) |
|
1 |
2 |
1 |
2 |
|
-" α — - ) 1" ) E1 E2. , - ) 1 + * " 1
) #*0 )+ , ) -* )
& " ' (":
d 2 = r12 + r22 + 2r1r2 cosα ,
*
|
d 2 |
− r 2 |
− r |
2 |
|
|
cosα = |
|
1 |
2 |
= −0, 238 . |
(3.2.8) |
|
|
|
|
||||
|
|
2r1r2 |
|
|
|
= *, " (( (3.2.6) (3.2.7) (3.2.8), " ( (1 2 &-
- ( ! & )
|
|
|
|
|
|
|
|
|
|
|
1 |
|
|
|
q2 |
q |
2 |
|
|
|
q q |
|
|
|
|
|
|
||
|
|
|
|
|
|
E = |
|
|
|
|
|
|
1 |
+ |
|
2 |
|
+ 2 |
1 |
2 |
|
cosα . |
|
|
|
||||
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|||||||
|
|
|
|
|
|
|
|
|
4πε |
0 |
|
r 4 |
r |
4 |
|
|
|
r |
2 r |
2 |
|
|
|
|
|
||||
|
|
|
|
|
|
|
|
|
|
|
|
|
1 |
|
2 |
|
|
|
1 |
2 |
|
|
|
|
|
||||
! " ) & + ' & ( |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|||||||||||
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
||||||
|
|
1 |
|
|
|
|
|
(1 0 − 9 |
) 2 |
|
|
|
( 2 1 0 − 9 |
) 2 |
|
|
|
|
|
1 0 − 9 2 1 0 |
− 9 |
||||||||
E = |
|
|
|
|
|
|
|
|
|
|
|
|
+ |
|
|
|
|
|
|
|
+ 2 |
|
|
|
|
( − 0 , 2 3 8 ) = |
|||
|
|
|
− 1 2 |
|
|
|
|
|
4 |
|
( 0 , 0 7 ) |
4 |
|
2 |
2 |
||||||||||||||
|
4 π 8 , 8 5 1 0 |
|
( 0 , 0 9 ) |
|
|
|
|
|
|
|
( 0 , 0 9 ) ( 0 , 0 7 ) |
|
|
||||||||||||||||
3 |
H |
|
|
|
" |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|||||||||
= 3 , 5 8 1 0 |
|
= |
3 , 5 8 |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|||||||||
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
13
% %&-
3.2.01. 3 (1 * 2 &- ( &, 1 # "
) 1" & & +) ' (" ) q1 = 8·10–9 q2 = – 86·10–9 . ( ) 1" ' (" ) r = 10 ).
3.2.02. *- -* ) # 0 ( & & + ' ("+ " & + q. 3 (1 * ( ! $ -
-* , & ' ' (" ".
3.2.03. " + ' (" 10–7 "( ( '" ( 8 ) "- "- . " * (1 * !0 ( &, 1
( 5 ) ' (".
3.2.04. & & + ' (" q1 = 2q q2 = –q "( ( ( d "- "- . 3 1 & (), "(# & ' 2 ' ("+, - (1 * ! ( 0.
3.2.05. , & '" " )( & & +) ' (" ) q1 = 40 q2 = –10 , "(# ) ( ( d = 10 ) "- "- . " *
(1 * ! ( &, " - ' (" r1 = 12 )
- r2 = 6 ).
3.2.06. = *$ " ) R = 8 ) ' (", ) "-
+ *0 τ = 10 /). (1 * ! 2 &-
- ( &, " & *$ ( r = 10 )? ! * -% ' ) (1 ( E ' )
( ( " $ *$ .
3.2.07. ! % ' (", ) " +
*0 σ = 1 /)2. 3 (1 * ! 2 &- ( $ -
% +.
3.2.08. ! () " " L = 1 ) ' (", ) " +
- ". 3 & 2- ' (", (1 * E (
( = 0,5 ), 1 ) " * " ( " "- ' - $ , 200 /).
3.2.09.! () ( " L = 1 ) ' (" q = 40 ), )
" + ". 3 & (1 ( E &, 1 " 1 ( d = 1,5 )
$ .
3.2.10.! " " L = 40 ) - ) " ()+) -). ! - " ) " ' (" q = 10 ). " * (1 * (
E " &, 1 + -' &-( - - " - , ( d = 10 ) + 2- - .
14
3.3. ") *% % %.
") -& /-' *-!-* *
( 1" ( (1 2 &- ( " & + & ( " *' * ( ) .,
% ) ' & " 0# ) ' ): (1-
2 &- ( '* ' * 0 ' ) 0 *
)) 2 & ' (" 2 " 2 &-
0 ( 0 ε0.
|
1 |
qi , |
|
(EdS) = |
|
(3.3.1) |
|
s |
ε0 i |
|
-" dS = dS·n. ! 2 ) dS — 2 ) - , n —
) 2 ) dS, (EdS) = E·dS·cosα — E
'* 2 ) dS, α — - ) 1" ) E dS, qi —
)) ' (", "(# ( 2 . A ' ("
, 0. ( & ( +- "-
( ' (" ) 1 ' *:
qi |
= ρdV , -" ρ – B@) ( * ' ("; |
i |
V |
qi = σ dS , -" σ – ( * ' (";
iS
qi = τ dL , -" τ – ( * ' (".
iL
-& (, "+ )+ *' )+ ., "-
0 ( 1" - ') 1 *0 +& ( - & -
(3.3.1). , ' ' & *- " ( ' (", '" 0#-
" & : " ( (- " ( ) 1 " *
*, '* 0 ) 1 " * & ) ".
15
3 (1 & + ( " ( ))-
& + " ' (" — % &, $" & .
)-* )+ ) 3 !- $% %& |
|
)-* ) 4. 3 (1 * 2- |
|
&- ( " |
R, |
' (1- B ) *0 ρ ( . |
|
3.6). ! * -% ' ) (- |
|
1 ( ! ( ( " $ |
- |
. |
|
3 !- . ! " * " ) (1 * ( !1 –
( r1 $ (1 * ( !2 – 1 -
( r2 $ .
+ ) % ) . . 0 & + )
" ( # ( +& ( - & (3.3.1)
" 1 + 0" * ( " 0# (:
. E = const 0 & " ( &, & '
+ 0;
. E dS E dS . +) ), - ( ) ' "
(3.3.1) " 1 + * α = 0°, α = 180°.
' 1 )) (, & * . " ) &
" + * " % + " r, $& ) R. ! 2 )
0 & + (0 ( ' 1 + + (: E = const
E dS 0 & ). . 3.6.
) " * 0 0 & )+ . (3.3.1) " ( -
1 # ' (1- :
1. |
|
(E dS) = |
|
E dS cos 0 = E |
|
dS = E 4π r 2 |
|
|
|
1 |
|
1 |
1 |
|
1 1 |
|
S1 |
|
S1 |
|
|
S1 |
|
|
|
|
|
|
16 |
|
|
1 |
ρdV = |
1 |
ρ dV = |
1 |
ρ |
4 |
π r13 . |
(3.3.3) |
|
|
|
|
|||||
ε0 V |
ε0 V |
ε0 3 |
|
|
||||
1 |
1 |
|
|
|
|
|
! ( ) & + (3.3.2) (3.3.3) ' *:
E 4π r 2 |
= |
1 |
ρ |
4 |
π r3 |
, |
|||
|
|
|
|||||||
1 |
1 |
|
ε0 |
|
3 |
1 |
|
||
|
|
|
|
|
|
||||
" # ( ": E = |
ρr1 |
. ", & (1 * |
|||||||
|
|||||||||
|
1 |
|
|
3ε0 |
|
|
|
|
|
|
|
|
|
|
|
|
|
) ' (1- ' $ % .
2. |
|
(E |
dS) = |
|
E dS cos 0 = E |
|
dS = E |
4π r 2 |
|
|
2 |
|
|
2 |
2 |
2 |
2 |
|
S2 |
|
|
S2 |
|
S2 |
|
|
|
|
1 |
|
ρdV = |
|
1 |
ρ dV = |
1 |
ρ |
4 |
π R3 . |
|||
|
|
|
|
|
|
|||||||||
|
ε0 V |
|
|
|
|
ε0 V |
ε0 3 |
|||||||
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
-& .1 ( |
(3.3.4) |
|
|
|
|
|||||||||
(3.3.5), & ): E = |
|
ρ R3 |
|
|
|
|
|
|
|
|||||
|
|
|
|
|
|
|
|
|
|
|
|
|||
|
|
|
|
|
|
|
|
|
|
|
|
|||
2 |
|
|
3ε |
|
r 2 |
|
|
|
|
|
|
|
||
|
|
|
|
0 |
|
|
|
|
|
|
|
|||
|
|
|
|
|
2 |
|
|
|
|
|
|
|
|
|
. % & ' ) * A(r) "- |
|
|
|
|
||||||||||
. 3.7. |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
(3.3.5)
-
17
% %&-
3.3.01.*' ( ) ., (1 * (, '"- '-
(1 & *0. ( * ' (" λ .
3.3.02.3 (1 * ( % &- ", ' (-
1- ' (" ) q. " " r, — R.
3.3.03.3 (1 * ( % + " R, ' (1-
*0 σ . ! * -% ' ) ! -
( ( " $ % +.
3.3.04.3 (1 * 2 &- ( "
R, ' (1- B ) *0 ρ = ρ0(1 – r/R), -" r — (
$ , ρ0 — * ' (" $ . ! * -% '-
) ! ( ( " $ % +.
3.3.05.3 (1 * (, '"- & , ' (-
1 *0 σ .
3.3.06. 3 (1 * ( - ", +
- & + ' (1 + *0 +σ .
3.3.07.3 (1 * ( - &- $ -
" " R, ' (1- B@) *0 ρ . ! * -%
' ) ! ( ( " $".
3.3.08.3 (1 * ( - &- $ -
" " R, ' (1- *0 σ . ! * -% ' ) ! ( ( " $".
3.3.09. " + + * + " ) R1 = 2 )R2 = 4 ) ' ("+, ) " + " +)
() τ1 = l /) τ2 = –0,5 /). " * (1 * ! (
&, "(# ( ( ( r1 = 1 ), r2 = 3 ), r3 = 5 ) .
! * -% ' ) ! r.
3.3.10. * ( (, # d = 1 ) ' (", )
" +: B ) B ) *0 ρ =100 /)3. 3 -
(1 * E 2 &- (: ' $* & +
, ) ) ( .
18
3.4." !1-% . %," % 2" .
") -& /-' *-!-* *
,-& 2 &- ( ( ( ( $ -
: |
|
|
|
|
|
|
|
|
|
|
ϕ = |
W |
, |
|
|
(3.4.1) |
|||
|
|
|
|
|
|||||
|
|
|
|
q |
|
|
|
||
'" * W – 2-(, " & ( " ' (" q. |
|
||||||||
!$ ( )+ & & + ' (" qi: |
|
||||||||
ϕ = |
1 |
|
|
|
qi |
. |
(3.4.2) |
||
|
4πε0 |
|
|
||||||
|
|
|
i |
ri |
|
2 &- ( 0 ' (" q ' & 1 &
2: |
|
A12 = q (ϕ1 − ϕ2 ) = qU , |
(3.4.3) |
'" * U = ϕ1 − ϕ2 – ' * $ .
" ' " ( (- 2 &- (
* - $*. !$* * 2 &- -
( ' 0& ( ), & , ' " ( ) " ' (" ) ' )-
) , 0: |
|
E dl = 0 . |
(3.4.5) |
L |
|
" * = E dl — $($( (1 2 &- (
' ) ) . " * ) " ) '+ * -
+) ) " ( 2 &- ( ( — )
.).
('* ) 1" (1 *0 $) 2 &- ( " @ (
):
E = −gradϕ , |
(3.4.6) |
-"
19
|
|
|
∂ϕ |
∂ϕ |
∂ϕ |
|
|
||||
|
|
gradϕ = |
|
; |
|
|
; |
. |
(3.4.7) |
||
|
|
|
∂ |
∂ |
∂z |
|
|
||||
|
A ( r ' (" q (1 * !, ' * - |
||||||||||
$ ( ) 1 " 0# ) ' ): |
|
||||||||||
|
|
|
|
|
2 |
|
|
|
|
|
|
|
|
ϕ − ϕ |
2 |
= |
|
! |
( |
r dr . |
(3.4.8) |
||
|
|
1 |
|
|
|
) |
|
|
|||
|
|
|
|
|
1 |
|
|
|
|
|
|
)-* )+ ) 3 !- $% %& |
|
|
|
|
|
|
|
|
|
||
|
)-* ) 5. *$ " R ' (1 ' (" ) q. " * $ |
||||||||||
& *$ " ( - . " * - |
|||||||||||
(1 * ( & 2 . 3 & , -" (1- |
|||||||||||
* ) ) *. |
|
|
|
|
|
|
|
|
|
||
|
3 !- . "( ' $ '$ ' * ) * ' (- |
||||||||||
1 + - " ) * |
|
|
|
|
|
|
|
||||
', 1"+ ' + " - |
|
|
|
|
|
|
|
||||
) + ' (" dq. ' - |
|
|
|
|
|
|
|
||||
1 )) ( ( . 3.8), & |
|
|
|
|
|
|
|
||||
(1 * (, '" ) ( ' (- |
|
|
|
|
|
|
|
||||
" ) |
dq, 1 # ) $ - |
|
|
|
|
|
|
|
|||
- " ), & *$ |
|
|
|
|
|
|
|
||||
" * . (0- |
|
|
|
|
|
|
|
||||
# dE ' ) & 1 0 (. |
|
|
|
|
|
|
|
|
|
||
|
!$ & &- ' (" dq, |
|
|
|
|
|
|
|
|||
"( ' (3.4.2), ) 1 + * ': |
|
|
|
|
|
|
|
|
|||
dϕ = |
dq |
, -" r = R2 + x2 , |
|
|
|
|
|
|
|
|
|
|
4πε0r |
|
|
|
|
|
|
|
|
|
|
-" $ - ' (1- |
|
|
|
|
|
|
|
||||
" " ( ( ": |
|
|
|
|
|
|
|
|
|
|
1 |
q |
dq |
|
|
1 |
|
|
q |
|||
ϕ = |
|
|
|
= |
|
|
||||||
|
|
|
|
|
|
|
|
|
|
. |
||
4πε0 |
0 |
|
|
4πε0 |
|
|
|
|||||
|
|
|||||||||||
|
R2 + x2 |
|
|
|
|
R2 + x2 |
20