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Unformatted text preview: ECE 3209 — Electromagnetic Fields University of Virginia Fall 2009 Homework # 7 — Steady Electric Currents and Ohm’s Law Due: Friday, October 23 1. In class, we noted that the solution to Laplace’s equation at any particular point is the average of the potential surrounding that point. To demonstrate this, find the average potential over a spherical surface of radius R due to a point charge q located outside the sphere and show that this is equal to the potential at the center of the sphere. 2. Two concentric metal spherical shells of radius a and b , respectively, are separated by a conducting material of conductivity σ . If the metal shells are maintained at a potential difference of V volts, (a) (b) (a) what current flows from one shell to the other? (b) What is the resistance between the shells? (c) Notice that the outer radius is immaterial if b a . In view of this, what current would flow between two metal spheres, each of radius a , immersed deep in the sea and held far apart, if the potential difference between them is...
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This note was uploaded on 10/16/2010 for the course ECE 309 taught by Professor Weikle during the Fall '08 term at UVA.
- Fall '08