Field from a filament *
On a nylon filament 0.01 cm in diameter and 4 cm long there are 5.0⋅108 extra electrons distributed uniformly over the surface. What is the electric field strength at the surface of the filament:
((a)) in the rest frame of the filament?
((b)) in a frame in which the filament is moving at a speed 0.9c in a direction parallel to its length?