6B_Ch_20_GG

# Edges of the dielectric act as a second pair of

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Unformatted text preview: d in the absence of an electric field Dielectrics – An Atomic View, cont • An external electric field is applied • This produces a torque on the molecules • The molecules partially align with the electric field Dielectrics – An Atomic View, final • An external field can polarize the dielectric whether the molecules are polar or nonpolar • The charged edges of the dielectric act as a second pair of plates producing an induced electric field in the direction opposite the original electric field The result of polarization Table of Some Dielectric Values V for a Uniformly Charged Sphere • A solid sphere of radius R and total charge Q • For r &gt; R, • For r &lt; R, V for a Uniformly Charged Sphere, Graph • The curve for VD is for the potential inside the curve – It is parabolic – It joins smoothly with the curve for VB • The curve for VB is for the potential outside the sphere Problem Solving Strategies – Electric Potentials • Conceptualize – Think about the charges or the charge distribution – Image the type of potential they would create • This establishes a mental representation – Use any symmetry in the arrangement of the charges to help you visualize the potential Problem Solving Strategies – Electric Potentials • Categorize – Individual charges or a distribution? • Analyze – – – – – Scalar, so no components Superposition principle is algebraic sum Signs are important Changes in potential are what is important The point where V = 0 is arbitrary • But usually at a point infinitely far from the charges Problem Solving Strategies – Electric Potentials, cont • Analyze, cont – For a group of individual charges, use the superposition principle – For a continuous charge distribution, integrate over the entire distribution – If is known, the line integral of can be evaluated Problem Solving Strategies...
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## This note was uploaded on 02/03/2010 for the course NEUROSCI 101A taught by Professor Scheibell during the Winter '10 term at UCLA.

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