B-field Definition and 103 Threads

Can someone explain to me how a neutron star (I'm assuming that it has no charge even on the microscopic level) can have a magnetic field? And even if I assume that there is some residual charge left after the collapse, how could the magnetic poles point in significantly different direction...

Two parallel wires repel each other with a force per length of 1.00*10^-3 N/m when spaced a distance of 2.50 cm apart. If one wire has a current of 100A, what is the current in the other wire? Don't know where to start this one.

Hey! I am trying to get a rough estimate for the B-field (from a electromagnet) required to levitate a train. Assuming the train is of mass M, the force required to lift it and hold it at a distance D would have to equal M x g right? But how do i estimate the b-field an electromagnet...