Question

Which part of the bar magnet attracts more iron filings?

Answer 1

The closer together the field lines are, the stronger the field. As you can see the field is very strong in the center of the magnet, but because they are mostly contained in the magnet itself, the field is very weak in the air near the center. Since the field lines form loops, they have to enter in one place and leave at another, the two poles, here they must be much closer together even in the air, and the field is therefore stronger. These places are the poles.