Question

Why do we need to TAP THE BOARD when we want to see the effect of bar magnet on iron fillings? Since the Iron fillings are magnetic substance wouldn't they arrange automatically due to the action of bar magnet as soon as they are sprinkled?

Answer 1

Answer:

no they wouldn't arrange themselves..

they do not get much attractive force to set themselves in field lines.

that's why we need to tap the board till they set themselves in position.

this might be because the iron is powdered .