Science Puzzle
Which Magnet Wins the Tug of War?
A steel paperclip sits on the table. On one side, a big powerful bar magnet 8 centimetres away. On the other, a feeble little fridge magnet just 2 centimetres away.
Both magnets pull on the paperclip at once. Which one wins the tug of war?
The Answer
Almost always the little one. Magnetic pull does not fade gently with distance; it collapses. Move a magnet twice as far away and its grip on a piece of steel drops to a small fraction of what it was, far less than half. By 8 centimetres, even a powerful magnet is down to a whisper, while the weak magnet at 2 centimetres is still shouting.
You can feel this yourself: a magnet snaps onto the fridge only in the last moment of approach. Nearly all of its strength lives in that final centimetre.
The principle: Field strength falls off rapidly with distance. In a contest between strength and closeness, closeness usually wins.