am i right for this question:
why there is space between lines when iron filings are sprinkled on a bar magnet??

The reason for the creation of these pretty iron filing lines is that each little iron filing, when subject to a magnetic field, becomes a little dipole itself. This dipole feels the force of the magnet, and aligns in the direction of the field lines.This causes the clumping into lines that you see, as the opposite ends of the dipoles move together.