Why do fridge magnets ‘ripple’ when you rub them together?

Hint: Try taking another magnet and moving it slowly over the fridge magnet. Is it all magnetic? What pattern do the ‘magnetic bits’ form?

Solution: The magnetic sections are arranged in strips, with non-magnetic sections in between. When you line up a magnetic section of one magnet with a non-magnetic section on another magnet, the magnetic sections pull together, creating the force you can feel.

Interestingly, fridges are not magnetic if they have no magnets on them. The magnet induces a magnetic field in the fridge, by lining up the magnetic moments in the metal of the fridge wall. This is why fridge magnets are never repelled by any fridges (as you would expect if fridges were naturally magnetic, as eventually you’d be bound to find a magnet that had the same polarity as the fridge, and poles that are alike will repel each other).