How Can I Identify the Poles of a Magnet?
The easiest way is a compass: the end of the needle that normally points north is attracted to the magnet’s south pole and points away from its north pole. You can also use a magnet with marked poles, a Magnetic Pole Detector, or hang the magnet on a string and see which face turns north.
Four Ways to Find the Poles
Compass
Bring the magnet slowly toward the compass. If the needle’s north end swings away, you’re holding the north pole toward it.
Marked Magnet
A known north pole attracts the unknown magnet’s south pole and pushes away its north pole.
Pole Detector
Touch our Pole Detector to the face for an instant N or S reading.
String Test
Hang the magnet (or an even-numbered stack) from a thread so it can spin freely. The face that settles pointing geographic north is the north pole.
Keep Strong Magnets Away from the Compass
A strong neodymium magnet can flip or permanently re-magnetize a small compass needle. Approach slowly from a few inches away and stop as soon as the needle moves.
Mark the Poles Once You Know Them
Put a dot of paint or a small sticker on the north face of each magnet before assembly. It saves a lot of trial and error when you’re gluing pairs into a closure or project.