Title: Why does a compass needle deflect when brought near a bar magnet?

When a compass needle is brought near a bar magnet, it deflects due to the interaction of magnetic fields. According to the right-hand rule, the north pole of the compass points towards the south pole of the bar magnet and vice versa. This deflection occurs because the magnetic field of the bar magnet exerts a force on the magnetic domains within the compass needle, causing them to align in the direction of the magnetic field. This phenomenon is governed by the principles of magnetism and can be further understood through the study of electricity and magnetism in physics.

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