1. (Electrostatics)

2. (e)
(ion)

3. (positive electric
charge)
+1.610-19
Coulombs

4. :
(Static
Electric)

5. Outline
1. Introduction to
Electrostatics
2.

6. Introduction to
Electrostatic

7. Charges
-

8. Atomic Structure
 (nucleus) :
 (Proton)
 (Neutron)
 (Electron)

9. p+
n
e-
+1.6X10-19
-1.6X10-19
0
9.1X10-31
1.6749X10-27
1.6726X10-27

10. 600 B.C.:
(Thales)
(Electron
Electricity Elektron

11. Benjamin Franklin
1747

12. 1.
2.

13. 2
leather

14. 2

16. Conclusion :




17. Diagram :
+ - + -
- + - +
+ - + -
+ - + -
- + - +
+ - + -
Heat
+ +
+ +
+ +
- -
- -
- -

19. Conclusion :

1




20. Conclusion :


21. Diagram :
+4 -8
-2 -2
+ + + +
- - - -
- - - -
-4
-4
-4

24. Conductor &
Insulator

25. Conductor &
Insulator

26. Conductor &
Insulator

27. Conductor &
Insulator

28. Conclusion :
 2
 :
 :



29. Diagram :
- +
- +
- +
- +
+ +
+ +
+ -
+ -
+ -
+ -
- -
- -

30. (Electroscope)
1.)


32. (Electroscope)

34. Charging by Induction

35. Charging by Induction

36. Charging by Induction

37. Charging by Induction

38. Charging by Induction

39. Electroscope

40. Electroscope

41. Electroscope
+ -
+ -
+ +
-
-
-
-
-
-
+ ++ +
:

42. Electroscope

44. Example
A B C
. A C B
. A C B
. A C B
. A C B

45. Solution
B A
C A C B
B

46. Example

47. Solution
2
3
5
4

48. Example

49. Solution

50. 1.
2.
3.
4.

51. Charles Augustus Coulomb
“
”
1 2
2
KQ Q
F
R


52.  
1 2
2
KQ Q
F
R


55. Example

57. Example
x

58. Example
+ . x – C – . x – C
cm
+ . x – C

59. SOLUTION
A BC
+5x10-6 C -3x10-6 C+1x10-6 C
20 cm
10 cm

60. SOLUTION
A BC
+5x10-6 C -3x10-6 C+1x10-6 C
20 cm
10 cm FAC

61. SOLUTION
A BC
+5x10-6 C -3x10-6 C+1x10-6 C
20 cm
10 cm

62. SOLUTION
A BC
+5x10-6 C -3x10-6 C+1x10-6 C
20 cm
10 cm FBC

63. SOLUTION
A BC
+5x10-6 C -3x10-6 C+1x10-6 C
20 cm
10 cm FBC
FAC

64. Example
+5.6
-1.6
10

65. q
Q
Q
q

68. + -

75. 




76. “
q ”
qEF
q
F
E



77. Q Q
(q)
2
21
R
QKQ
F qEF 
2
r
KQq
qE 
2
r
KQ
E 

78. 1.
2.
NOTE

79. 3 m
A : 3x10-3 C
SOLUTION
B : 2x10-3 C C : -8x10-3 C
2 m

80. 3 m
A : 3x10-3 C
SOLUTION
B : +1 C : -8x10-3 C
2 m

81. 3 m
A : 3x10-3 C
SOLUTION
B : +1 C : -8x10-3 C
2 m
EA

82. 3 m
A : 3x10-3 C
SOLUTION
B : +1 C : -8x10-3 C
2 m
EC

84. Example
e- 9 x 10–31 kg –1.6 x
10–19 c
3 x 10–4 N/c
.
e-
. e-

85. SOLUTION

86. Example
2
10
37

87. + +
mg
T
FE
37
SOLUTION

88. SOLUTION
+
mg
T
37
Tcos37°
Tsin37°
FE

89. Example
X10-5 kg
C
cm/s2
g = 9.8 m/s2

90. +
a = 20 cm/s2
mg
E
qE
SOLUTION

91. +
a = 20 cm/s2
mg
E qE
SOLUTION

92.   0E


93. A : +3 C B: +3 C

94. A : +3 C B: +6 C

95. A : -3 C B: -3 C

96. A : -3 C B: -6 C

97. A : +3 C B: -6 C

98. A : -3 C B: +6 C

99. A : +4x10-8 C B : +9x10-8 C
0.5 m
x (0.5 – x)

100. 



a

101. E = 0
2
r
KQ
E 
2.
a
KQ
Esurf )/( CNE

-a +a0
a

102. m
m
5 m
System I

103. m
m
U = 0
U = 10 m/s
System II

104. Earth
m
h
mg
Ep = mgh

105. Charge ; Q
q
R
F = qE

106. Ep
q
V
V

107. +Q
x
R1
y
R2
Vx Vy
+10 V +5 V

108. -Q
x
R1
y
R2
Vx Vy
-10 V -5 V

109. - Q Q
- Q Q
-
-
Q Q
Q
-

110. V
X
Y
+
Q
r
-Q
r

111. r
KQ
r
QK
V
r
KQ
r
QK
V
y
x






)(
)(
r
KQ
V 
memo

112. Q
x
30 cm
y
70 cm
Vx Ey = 3500 N/c

116. C
B : -3x10-4 C
A : +3x10-4 C

117. a

VA A a

B
(VB
a
KQ
V 
r
KQ
VB 

118. V = V
r
KQ
V 
a
KQ
V 
)(voltV
-a +a0
a
B
A
r

120. E
q B A
d
d
A B E
WA®B = qEd

121. q Q
q A B
Q r r
BA
F
r1
r2
WA®B = EB - EA

122. WA®B = qVB -qVA
WA®B = EB - EA
WA®B = q(VB -VA )
WA®B = qVBA

123. V
d
E
(V/m)
VAB A
B (V)
d (m)
A B
d
V
)( BAAB VVqW 
)( BA VVqqEd 
EdVV BA 
d
V
E AB


124. ก.
ข.
r
KQ
V 
qEdW 
)( BAAB VVqW 
AA qVW 
radius
KQ
VV surfaceinside 

125. Q : +10x10-6 C
10 cm 10 cm 10 cm
A BC