Feynman Cylinder Paradox
نویسندگان
چکیده
1 Problem An infinitely long wire with linear charge density −λ lies along the z axis. An insulating cylindrical shell of radius a and moment of inertia I per unit length is concentric with the wire, and can rotate freely about the z axis. The areal charge density on the cylinder is σ = λ/2πa and is uniformly distributed. The cylinder is immersed in an external magnetic field B exˆz, and is initially at rest. Starting at t = 0 the external magnetic field is slowly reduced to zero over a time T a/c, where c is the speed of light. What is the final angular velocity ω of the cylinder? that is particularly easy to analyze. However, it avoids a subtle point related to the return flux of the external magnetic field, as discussed in sec. 2.4. This problem is based on earlier discussions by McKenna [14] and by Romer [3].
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