Notes for Chapter 4. Gaussian Models

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Geometrical Optics in Continuum

Fermat’s Principle

Fermat’s Principle is

$$\delta s=\delta\int n\dd \ell=0$$

If we choose the path …

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Invariance of Euler-Lagrange Equations

E-L is deduced from the Hamilton’s principle

$$\delta S=\delta\int L(\bm q, \dot{\bm q}, t)dt …
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Energy of Electrostatic Field in a Triangle

Energy of a triangle

For a triangle \(ABC\), assume the points have potential \(\varphi_a,\varphi_b,\varphi_c\). As shown in Fig. ???, \(AB'\perp AC, AC' …

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