→ braceup:感謝感謝~＊*ˋ( ￣▽￣)ˊ＊* 03/22 00:28
※ 引述《braceup (QQ捲捲)》之銘言：
: Given the spherically symmetric potential field in free space, V = V*exp(-r/a),
: find: (a) the charge density ρv at r=a;
: (b) the electric field at r = a.
Poisson's equation
(▽^2)V=-ρv/ε0 ------->you can derive ρv
then
D=ε0*(-▽V)∣r=a
Ok!
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