複雜系統之簡介(梁鈞泰) - 中研院物理研究所- Academia Sinica
複雜系統之簡介(梁鈞泰) - 中研院物理研究所- Academia Sinica
複雜系統之簡介(梁鈞泰) - 中研院物理研究所- Academia Sinica
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Steady diffusion<br />
absorber<br />
ρ=0<br />
R<br />
Current through any surface at<br />
radius r must be constant:<br />
I = constant ~ C ρ 0 R<br />
by dimensional analysis ( 量 ).<br />
But I =J * area = J 4π r 2<br />
ρ 0<br />
<br />
So J = I/4πr 2 = C ρ 0 R/r 2<br />
is the current per unit area.<br />
Important to see that I ∝ R , not R 2 , because the current density J<br />
decreases as 1/R.
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