Electrostatics 14 30214

12.. 1600 : William Gilbert (amber).. 1785 : Charles Coulomb .. 1819 : Hans Oersted .. 1831 : Michael Faraday Joseph Henry .. 1873 : James Clerk Maxwell .3 Benjamin Franklin

3

45 (Electric Charges) 2 (C): 1 C 6.24x1018 1 A 1 s6

.3 7 (Conservation of Charge) :Q = NeN e = 1.6 x 10-19 Ce = -e e = +e 8 (electrical and conductor)

9 (Electrostatic Discharge)

1011 Electrical Induction

12

(Electroscope)13

.3 14 15

(Coulomb's law) (Charles Augustin de Coulomb) ( .. 2279)16 .3 17ke (point charge) :ke = 8.9875 x 109 N.m2/C2 =

= 8.8542 x 10-12 C2 / N.m2

18 3

19 (principle of superpositon)

6 1

20 1 +5.0 C -3.0 C21 2 5.3x10-11 m 22 3 4 A, B, C D 4 cm -2 C, 8 C, +4 C 12 C C

ABCD .3 23 4 q3 q1 q2 q1= q3=5.0 C, q2= 2.0 C a = 0.1 m

24 5 0.1 1 60

(Electric field)Faraday (source charge ) (test charge) 25 (Electric field) (E) (Q) (F) q0 26

F27

--------------------------------

28 (electric filed lines) A B 29 (electric filed lines)

30

(electric filed lines)

31

2 32 (electric filed lines)33

Q +Q +q +Q r F +q q

+Q+qrF34 A +5 x=0 B -10 x = 10 cm x=-5 cm 1AB .3 35 q1=7.0 q2= -5.0 0.3 x P 2

P36

37

38 3 A +4 B +16 30 cm B 39 A +8 B 30 A 20 B 440 r

r

(Uniform field)

41

42 43

44+mgFea

q

45 104 0.02 2 2 546 2 15 cm 3000 N/C P 1) A2) A3) A 6

47 0.40 kg = 37 g 10 m/s2 7 R 48

Q = r = 49

r 50

51 8 10 cm 20 1) 5 cm2) 3) 12 cm52

: N-m2/C53

(1) :

(2) :

(3) :

(net flux) 54 ()

(Gaussian surface) E

55qin E ()

56 (surface integral) 57 q 958

1059

11 (Energy potential) (Ep) q q q q q

A60 +q

A B

+q A B

+q B

61 q Q B A

62

B A

63

B A

64 Q1, Q2 Q3 R1, R2 R3

Q1 Q2

65 Q3 Q3 Q1 Q2

66 (Electric potential)

V = / EP = q = N Q1, Q2, Q3, , QN r1, r2, r3, , rN

67

6869 4x107 m/s 900 N/C 1270 10 C 50 V/m 1 1371 50 C 20 C 40 cm 1) 2) 50 C 40 cm 20 C 16 cm3) 2 C 1) 2) 1472 0.2 5x10-7 C 5 cm 60

15

73 12 V/m +3.0 C A C ABC 16

74 E 4x104 AB BC 10 5 -10-6 A C 17

75 4 cm -10 C 2, 4 6 cm 6 cm 4 cm 18

(capacitance)76

+Q-QVEEQ V77Q VQ = CVC = Q/VC (F)78 V Q Q V

79 .3 8081 .3 82 A d

83 ra rb

84 ra

a 85 (capacitor condenser)

86 87

(Series) 88

(Series) 89 (Series)

90

(Parallel) 91

(Parallel)

92

93 2 94

C1, Q1 C2, Q2

C1, Q1 C2, Q2

95 5 20 2,000 96 1 A B 6 12 24 97 2 4 F, 6 F, 12 F 1) 2) 3) 6 F 12 F 4 F4) 3. 20 98 3 20 12 30 99 4 A 2,000 B S A 1,600 A 4.0x10-3 F B

ABS100 5 A 2 B

101 6