Engineering and Applied Sciences Applied Physics 216 Lecture 13: Lecture 13
21 Feb 2017
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Ap 216 lecture 13 forces on and energies of dielectric materials. Discussed force on moving monopole and dipoles of charge distribution due to external fields. Discussed electric, polarization and displacement fields in a dielectric material. Except in x-ray physics these fields are usually assumed averaged over several atoms or unit cells of a crystal and this average rarely varies much over length scales smaller than those over which the fields vary. For statics problems this means we can consider equation (2) to take the form. P x av av av av av (3) Nonlocality in space in the linear approximation can be handled by an alternative assumption. P x dv f x x e x. P x t av ximation av x t. E x t d x t av av. E x t av can also be generalized. P x t t dv f x x t dt t e x t (4) (5) (6)
