First, my top recommendation is to use a magnet with known polarity. Find a magnet with clearly marked poles, and bring its north pole close to one end of the magnet you want to test. If they attract, that end is the south pole; if they repel, that end is the north pole.
The second method is to use a compass. Suspend the magnet with a thin thread, allowing it to rotate freely. Once it comes to rest, the end pointing south is the south pole, and the end pointing north is the north pole. This method is a little more complicated, but it's very effective!
The third method, which I use less often, is the solenoid method. However, I think this is a bit complex and more suitable for physics experts. It might be a bit challenging for everyday use by college students.
The last method is the small magnetic needle method. Buy some small magnetic needles and place them near the magnet to compare. Based on the principle that opposite magnetic poles attract, you can determine the polarity of the magnet. This method is also very effective and relatively simple.
