Final answer:
To determine the north and south poles of a magnet using another magnet, you can observe their interaction. If the north poles repel each other or the north pole attracts the south pole, the unknown magnet's pole is the south pole. If the north poles attract each other or the south pole repels the north pole, the unknown magnet's pole is the north pole.
Step-by-step explanation:
If you have one magnet with the north and south poles labeled, you can use this magnet to determine the north and south poles of another magnet by observing their interaction.
If the north pole of the known magnet is repelled by a pole of the unknown magnet on bringing them closer, that pole of the unknown magnet is its north pole. Otherwise, it is its south pole. This is because like poles repel each other.
Alternatively, if the north pole of the known magnet is attracted to a pole of the unknown magnet on bringing them closer, that pole of the unknown magnet is its north pole. Otherwise, it is its south pole. This is because unlike poles attract each other.