Physics 4322 Homework Set 2 January 24, 2012 Due: Tuesday, January 31, 2012 1. A wire has resistance R . Determine the resistance of a wire twice the length and half the diameter, assuming it is made from the same material. 2. A conducting sphere of radius a is embedded in a large volume filled with a material with conductivity . The sphere is held a constant potential V o with respect to the boundary, which may be assumed to be at infinity. Determine the current density J ( r ), the total current I , and the resistance R . (Hint: Laplace’s equation for V must be satisfied.) 3. Two concentric conducting spherical shells having inner and outer radii a and b , respectively, are separated by a weakly conducting material of conductivity . (a) If the potential difference between the spheres is V , what current I exists between the spheres? (b) What is the resistance R between the shells? 4. Suppose the conductivity of a material between two concentric cylinders is
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This note was uploaded on 02/20/2012 for the course PHYS 1101 taught by Professor Lowellwood during the Fall '10 term at University of Houston.