When a bar magnet is cut into 2, the two halves repel each other. Why?
What becomes the original north and south poles of that magnet?
When a bar magnet is cut into two pieces, each piece becomes a magnet on its own. The reason why the two halves repel each other is due to the nature of magnetism.
Magnetism is caused by the alignment of tiny atomic magnets called magnetic domains within the material. In a magnet, these domains are all aligned in the same direction, creating a magnetic field. When the magnet is cut, the alignment of the domains in each half is disrupted.
Cutting a bar magnet separates the magnetic domains into two parts. Each half retains its own set of magnetic domains and tries to realign itself to minimize its energy. In doing so, the two halves of the magnet become two separate magnets, each with its own north and south poles.
To determine which side is the north or south pole, you can use a compass. When one half of the magnet is placed near the compass, the needle will indicate the north pole of that half. The other half will then be the south pole.
In conclusion, when a bar magnet is cut into two pieces, each piece becomes a magnet and the two halves repel each other due to the misalignment of their magnetic domains. The original north and south poles are determined by using a compass to identify the poles of each half.