Iron, made temporarily magnetic
Why Do Magnets Stick to the Fridge?
A magnet turns the iron in the fridge door into a magnet, and the two attract.
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Step 1 of 5
Only some metals respond.
Iron, nickel and cobalt stick. Aluminium, copper and gold do not, which is why magnets slide off drink cans and modern fridge doors.
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Step 2 of 5
Iron is full of tiny magnetic regions.
Each region is already magnetic, but they point in random directions and cancel each other out. The metal seems unmagnetic overall.
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Step 3 of 5
A nearby magnet lines them up.
Bring a magnet close and the regions rotate to point the same way. Now their magnetism adds instead of cancelling.
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Step 4 of 5
Two magnets attract.
The temporarily magnetised steel is oriented so its opposite pole faces yours. Attraction is automatic and immediate.
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Step 5 of 5
Take it away and the effect vanishes.
The regions fall back to random directions and the door is unmagnetic again. Hard steel keeps the alignment — that is how permanent magnets are made.
Stroking a needle repeatedly in one direction with a magnet lines up its regions enough to make a working compass.
The short version
A magnet lines up the tiny magnetic regions inside steel, making the fridge door briefly a magnet too, so the two attract.
Try it yourself
Stroke a needle 30 times one way with a magnet, then float it on a leaf in water. It swings north.
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