Investigation with magnets

Question

Take the following method for an experiment with magnets.

Method:

1. Hold the magnet about 1 m above the desk
2. Place a paperclip at the end.
3. Add another paperclip until the chain cannot hold any more
4. Count the number of paperclips you can add to the chain.
5. Repeat the experiment 3 times

On trial 1 I got 4 paperclips, on trial 2 I got 3 paperclips and on trial 3 I got 3 paperclips. Why does this experiment give variable results? Could it be that depending on the position of the paperclip on the magnet, it could have different magnetic strength?

Answer 1

Could it be that depending on the position of the paperclip on the magnet, it could have different magnetic strength?

Yes. The external magnetic field depends on the shape of the magnet and the direction of its magnetization. It is usually larger towards its corners/edges. This leads to some sharp steel tools (screwdrivers, scissors etc.) sometimes having enough magnetic stray field from their tips to also hold onto light items such as paperclips/bolts.

Another very important factor is the movement of the clips. Especially if you do that manually, the forces of the swinging clips can be enough to sever the attachment, even if the holding force would be sufficient for a perfectly still scenario.