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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 > R, • For r < 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
– 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
– 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.
- Winter '10