1
$\begingroup$

We all know that a magnetic compass needle when suspended by a thread and placed near a bar magnet, will rotate. However like a bar magnet, will the magnetic compass needle get attracted towards the magnetic pole? That is, will the north pole of compass move towards the south pole of the bar magnet (besides rotating)?

$\endgroup$

1 Answer 1

2
$\begingroup$

The field of a bar magnet has a lot of divergence in it (the field rapidly gets weaker with distance) - and that is the prerequisite for attracting another bar magnet (like a compass needle). If you think of a bar magnet as a "North monopole" and a "South monopole", then one will be in a stronger field than the other - which is why there is a net attraction. Of course that's not really how magnets work, but I believe it helps your intuition.

In a purely uniform magnetic field, there is no attractive force on a bar magnet - only torque. But that is a situation that hardly ever arises.

So the answer is "yes".

NB: the North Pole of Earth is actually a magnetic South Pole - that which we call the North Pole of a magnet is the one that points North...

PS: a typical example of "one magnet attracting another because of the divergence of the field" is this picture:

enter image description here

The strong magnet in the MRI imaging system has a field that diverges outside of the bore - and this is strong enough to pull things like wheelchairs into it (if those wheelchairs are ferromagnetic). These accidents are all too common - and sometimes there are people between the object and the scanner, and that's not a good place for them to be...

$\endgroup$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.