The magnetic field lines for a solenoid look like this:
As one can determine from the right-hand rule, the left side of the diagram contains the north pole and the right part the south pole. It makes sense to me that, near the north pole, the north pole of another magnet would move towards the solenoid's south pole. However, can somebody explain why the magnetic field lines inside the solenoid point towards the north pole? Does this mean if another magnet's north pole was placed inside, it would be attracted to the north pole of the solenoid?
Best Answer
It is believed that magnetic monopoles do not exist [there is a lot of debate going on, one research group even claimed to have detected magnetic monopoles].If magnetic monopoles do not exist, then the divergence of the magnetic has to be zero [to make the flux over any closed surface zero]. This is possible only if magnetic field lines form closed loops [you see there is no other magnetic "charge" where the lines can terminate]. So, inside a solenoid or bar magnet, the field has to be opposite to its direction outside. This can be even tested by placing a magnetic compass inside.