a. Find an expression of the final angular velocity ω of the cylinder in terms of the symbols given and other constants.
Given constants:
## Braking up
An infinitely long wire with linear charge density −λ lies along the z-axis. An infinitely long insulating cylindrical shell of radius a is concentric with the wire and can rotate freely about the z-axis. The shell has moment of inertia per unit length I. Charge is uniformly distributed on the shell, with surface charge density 2πaλ.
The system is immersed in an external magnetic field B0z^, 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.
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