### Re: Why does sugar water increase magnetic attraction?

Date: Mon Dec 10 16:10:43 2001
Posted By: John Moulder, Faculty, Radiation Biology, Medical College of Wisconsin
Area of science: Physics
ID: 1007934493.Ph
Message:

sugar water and magnets A grade school experiment:

"During a 7th grade experiment a paper clip in a plastic bottle was attracted by a horseshoe magnet through air, tap water, salt water, ice water, and sugar water. The distance of attration was basically the same except through sugar water, which caused the clip to be attracted at a significantly greater distance!"

The exact physical set-up is not described, but I assume that the paper-clip was in the bottom of the bottle and the magnet was above it. In this case the distance at which the paper clip can be attracted in determined by its weight. The weight of the paper clip, in turn, is determined by the density of the liquid. The denser the liquid is, the less weight the paper clip will have.

Experiments:
• The effect of the sugar solution should be roughly proportional to the sugar concentration.
• Any other solute should have the same effect, but there is very little that is as soluble in water as sugar.
• If the water is replaced by a less dense liquid (ethanol?) the distance of attraction should decrease, and if it is replaced by a thicker liquid (oil?), the distance should be greater.
• Increase the buoyancy of the paper clip by tying a wooden match stick to it, or decrease the buoyancy by adding a lead weight.

Thought experiment -- what happens if you try this in the international space station?

One complication -- as the density of the liquid increases there will also be an increase in drag (friction) on the paper clip, this will counteract some of the increase in buoyancy.

This one was tricky, since I looked at EM theory for an explanation, rather than at "simple physics". I actually had to put this one out on the net for help.

John Moulder
Cancer Researcher
Medical College of Wisconsin

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