? ? 1 : ? ?(Electric Field) (????14)

1
? ? 1 ? ?(Electric Field)(????14)
???????????????? ????????(Coulomb electrostatic
law) ?????? Q ???????q ??
r,???????? ?????????(permittivity
constant) ?0 ?
1/c2k0 1/(3.00 x 108)2x4?x10-7
8.85 x 10-12 C2/(Nm2)
(SI units) ko
1/4??o 8.99 x 109 Nm2/C2

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The dielectric constant is function of
temperature, frequency, pressure.. etc.. ?r(T, ?,
P,..)
3
? ?(Electric fields)-- ??/????

• ???????????? q ?????
• ????qi??????

4
? ?(Electric fields)

• ???(electric line)????????
• ?????,?????
• ???????????????????????
• 3.??????????????????
• 4.????????
• 5.????????????
• ???????????????,??????????

????? ??????
5
Rules for Drawing Electric Field Lines-Proposed
by M. Faraday -A useful tool to describe the
direction and intensity of the electric field and
its description.

• The lines must begin on a positive charge and
  terminate on a negative charge.
• In the case of an excess of one type of charge,
  some lines will begin or end infinitely far away
• The number of lines drawn leaving a positive
• charge or approaching a negative charge is
• proportional to the magnitude of the
  charge.
• Field lines always cannot intersect.

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???????????? (????????)
(b)????????
(c)??????????
(a)????????
(f)????????????????
(g)???????????????
(d)?????????
(e)??????????
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??(Electric Potential)-A scale physical quantity

• ???q?????(??)
• ????qi????
• ??????
• ???????,?????????????,??????????????
• ???,a, b???????
• ???????
• ???(equipotential surface)????????????
• ????????????

????? ??????
8

• The equipotential lines are the dashed blue lines
• The electric field lines are the brown lines
• The equipotential lines are everywhere
  perpendicular to the field lines

E and V for a Point Charge
E lines and V surface for an Infinite Sheet of
Charge
E and V for a Dipole
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(No Transcript)
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?????????????

• ???????????????????????,???????????????????????

???????????????
???????????
(1) ?????(source) (2) ?????(detector) (3)
U-???(U-probe) (4) ???????(drawing paper)
(a) ?????? (b) ????? (c) ????? (d) ???????? (e)
????
?????????
????
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????????????????????
(a) ?????? (b) ????? (c) ????? (d) ???????? (e)
????
12
?????????
????? (current detector)
U-???(U-tape probe)
??????? (draft A4-paper)
???????(Source)
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? ? 1 ? ?(????14)
?????????????,?????????????? ???????3? ? U??? ?
9???1k ? ???????? ??????? ??? ????? ??????

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• ? ? ? ?
• ????1???????????,??????????????X,Y??????????,?????
  ????,?????????(????) ?
• ????????????,????????U???,????????????????????C??
  U????????,????????????,??????C????
• ????????C??????,????????C????????CC ?
• ????2????1?B??D?E?F?G.?????????(????6??????,????
  ?????,?????????,?????????????????) ?
• ???????????,??????????????
• ?????????,????????????(X??Y?)????,??????????????
  ??

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? ? ? ? 1. ????????(dc power supply-1)???????(pl
ate capacitor-4)?XY????,?????????(q, -q)????E?
?????????????,?????????????(off)
(1) ?????(Source) (2) ?????(ammeter) (3)
???U-??? (U-tape probe) (4) ??????? (draft
A4-paper)
?????
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????

• 2. ?8????R????????????(4)?XY?????,?????????(1)??(?
  ????,???????????????,????17??)
• 3. ???(ammeter)(2)??????????????(??C?),
  ?U???(3)?? U????????????
• 4. ????????(null measurement)????????U???,???????
  ?(?V 0), ???????(I 0)????????, ????????????
• 6.???????????????????A, B, C, , H???????,
  ????????????
• 7. ????????????(E)
• 8. ??????(????????), ?????????

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3.???U-??? (U-tape probe)
2. Detector (Ammeter)
?????????
???????????? (draft A4-paper)
3.???U-??? (U-tape probe)
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???????