[理工] [電磁] 靜電學 虛像法
清大考古題
94年 電機領域聯合招生 電磁學A
第3題
A charge q(1 C) placed at a distance d(1cm) from the center of an isolated
conducting shell of inner radius a(2cm) and outer radius b(3cm). The
conducting shell is also covered uniformly by a dielectric material of
dielectric constant 2.0 and thickness 1 cm, as shown in figure 1. Find
(a)the electric field at the center of the sphere
(b)the force F, on the conductor and
(c)identify all the charges(including their locations) in this system, e.g.,
induced surface charges and volume charges, etc. Please find the density
of these charges located in region r≧b.
(d)electric potential at point P(on conductor outer surface)
figure 1：http://i950.photobucket.com/albums/ad347/glassbuoy/08a8aa9c.jpg
解法及疑問：
(a)求在圓心的電場
孫超群的解法是：在球殼外 z = -(a^2)/d 處有虛像 q' = -(a/d)q
電場就是 球殼內的電荷對球心造的電場 + 球殼外虛像對球心造的電場
我的疑問是，球殼的厚度以及介電質的厚度，對虛像的位置及電量有影響嗎？
解答：http://i950.photobucket.com/albums/ad347/glassbuoy/c617bed6.jpg
有人可以幫忙說明一下嗎？從球殼內電荷開始，如何感應電荷...感激不盡
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◆ From: 220.142.178.93
※ 編輯: CGMS 來自: 220.129.38.126 (09/23 16:45)
※ 編輯: CGMS 來自: 220.129.38.126 (09/23 16:48)
※ 編輯: CGMS 來自: 220.129.38.126 (09/23 16:52)
推
09/23 23:28, , 1F
09/23 23:28, 1F
→
09/23 23:29, , 2F
09/23 23:29, 2F
→
09/23 23:30, , 3F
09/23 23:30, 3F
→
09/23 23:31, , 4F
09/23 23:31, 4F
→
09/23 23:31, , 5F
09/23 23:31, 5F
※ 編輯: CGMS 來自: 220.142.179.50 (09/24 07:39)
→
09/24 11:24, , 6F
09/24 11:24, 6F
→
09/24 11:25, , 7F
09/24 11:25, 7F
→
09/24 11:26, , 8F
09/24 11:26, 8F
→
09/24 11:26, , 9F
09/24 11:26, 9F
推
11/29 12:13, , 10F
11/29 12:13, 10F
→
11/29 12:14, , 11F
11/29 12:14, 11F
→
11/29 12:15, , 12F
11/29 12:15, 12F
→
12/15 00:24,
5年前
, 13F
12/15 00:24, 13F