# 59 q1 q1 d a q2 q1 2 c 4b 2 4a 2 2 4 b a q1

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Unformatted text preview: nd carries a total charge Q1. Concentric with this sphere is a conducting spherical shell of inner radius b and outer radius c, which carries a total charge Q2. What is the surface charge density, σb, on the inner surface of the outer spherical shell (r = b)? 59% − Q1 − Q1 (D) (A) Q2 − Q1 2 (C) 4πb 2 4πa 2 2 4π (b − a ) + Q1 + Q1 (B) (E) 2 4πa 4πb 2 Charge must be induced to insure E = 0 within conducting shell Spherical symmetry & Gauss’ law determines E Qenclosed ∫ E ⋅ dA = ε0 E ⋅ 4π r 2 = 0 Qenclosed = Qa + Qb = Q1 + (−Q1 ) σ= − Q1 4πb 2 Physics 212 Lecture 29, Slide 7 Physics 212 Lecture 29, Slide Gauss’ Law Q1 = - 3 µC A solid conducting sphere of radius a is centered on the origin, and carries a total charge Q1. Concentric with this Q2 = 5 µC sphere is a conducting spherical shell of inner radius b and outer radius c, which carries a total charge Q2. Which of the following graphs best represents the magnitude of the electric field at points along the positive x axis? 70% a < r < b: E = kQ1/r2 r > c: E = k(Q1+Q2)/r2 Q1 = ­3µC r < a: E = 0 Eliminate (a) and (c) b < r < c: E = 0 Eliminate (e) Q1 + Q2 = +2µC For r > c, E must be less than the continuation of E from a to b Physics 212 Lecture 29, Slide 8 Physics 212 Lecture 29, Slide Electric Potential Q1 = - 3 µC A solid conducting sphere of radius a is centered on the origin, and carries a total charge Q1. Concentric with this Q2 = 5 µC sphere is a conducting spherical shell of inner radius b and outer radius c, which carries a total charge Q2. If the inner conducting sphere were replaced with an insulating sphere having the same charge, Q1, distributed...
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## This note was uploaded on 02/18/2013 for the course PHYS 212 taught by Professor Kim during the Fall '08 term at University of Illinois, Urbana Champaign.

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