Water and Magnets

I am working on a science fair project about magnets. I am testing how magnetism works with substances. We tried a ziploc bag filled with water as the substance between the magnet and the metal. With most of our other substances(such as wood, thermocol etc.) the magnet was sticking to metal with the substance in between. Where as the magnet and metal did not stick together with water in between. magnet still moved the compass with water in between. From your website I thought since water does not have any effect on magnetism and ziploc bag by themselves did not have any effect either, the magnet and metal should stick. I am puzzled as to why it did not stick.
- Praneil (age 8)
PA, USA

Great question. Based on what we know about water and magnetism (https://van.physics.illinois.edu/qa/listing.php?id=368), I don't think that the water had much of any effect on the magnetism itself. The wood and the water would be very similar that way. So I think that it's just something about the floppy bag that makes it hard for the magnet and the (iron?) metal to get close enough to stick. I bet if you tried a different fluid in there, say cooking oil, it would act a lot like the water. you could also try two very thin sheets of wood or aluminum or something else hard, held together rigidly with a layer of water or oil in between. I bet they will act just like a single slab of wood or aluminum with the same total thickness. Why not give it a try?

Mike W.

(published on 01/21/2016)