Push two bar magnets together end to end. Sometimes they snap together before you expect it. Flip one around, and they spring apart before they even touch.
In the Fields topic you saw the rule: like poles repel, and unlike poles attract. This lesson puts the rule to work. Look at the two poles that face each other, and predict.
Here are three pairs of bar magnets on a bench, end to end. Between each step, one magnet is turned around.
In the first pair, an N pole faces an N pole. The magnets repel, because like poles face each other.
One magnet is turned around. Now an N pole faces an S pole. The magnets attract, because unlike poles face each other.
The other magnet is turned around too. Now an S pole faces an S pole. The magnets repel, because like poles face each other.
Two bar magnets face each other, S pole to S pole. Do they attract or repel?
One magnet's N pole faces another magnet's S pole. Do the magnets attract or repel?
Petra says two magnets can push each other apart without touching. Is Petra correct?
The rule also runs in reverse: watch what a pair of magnets does, and you can name the poles that face each other.
Two ring magnets sit on a wooden rod. The top one floats above the bottom one, held up without touching it. Which kind of poles face each other?
The floating magnet is forced away from the one beneath it, so the pair repel.
Like poles repel.
Like poles face each other — N facing N, or S facing S.
Two bar magnets are brought together, N pole facing N pole. What happens?
A bar magnet hangs level from a string. Jude brings another magnet's N pole slowly toward the hanging magnet's N end. What does the hanging magnet's N end do?
Two toy train cars have magnets at their facing ends. Pushed gently toward each other, the cars roll apart without touching. Which pole arrangement explains this?