Figure (a) shows a narrow charged solid cylinder that is coaxial with a larger charged cylindrical shell. Both are nonconducting and thin and have uniform surface charge densities on their outer surfaces. Figure (b) gives the radial component E of the electric field versus radial distance r from the common axis. The vertical axis scale is set by E, - 3.9 x 103 N/C. What is the linear charge density of the shell?

An infinitely-long, hollow, conducting cylinder carries a uniform current I that flows parallel to its axis and into the paper. Its inner radius is a and its outer radius is b. Derive expressions for the magnetic field for (a) a < r < b and (b) r > b Note: See image for the figure.

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