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Effect of magnetism on water molecules

  1. Jun 15, 2012 #1
    Does anybody have ideas for experiments that I can perform to investigate the title? I am working on a science project at the moment.

    Thanks very much for any help given.
  2. jcsd
  3. Jun 15, 2012 #2
    You probably don't mean magnetic fields in general. You are probably thinking of looking at the interaction between pure water and static magnetic fields. The interaction between pure water and static magnetic fields is very weak.
    I don't think there are any low tech experiments that can be done with static magnetic fields. The interaction between magnetic fields and water molecules is generally too weak.
    Radio frequency experiments can be done that involve the interaction of water with oscillating magnetic field. There is the trivial example of water being heated in a microwave oven. Radiofrequency oscillations of a certain frequency are absorbed by water molecules, creating heat. This is a resonance effect that involves both magnetic and electric fields. However, I am not sure how far you can go with this unless you can get a radiofrequency generator that you could adjust. Microwave ovens have controls with regards to the amplitudes. However, you can't do anything else without modifying the oven.
    Nuclear magnetic resonance is a phenomenon based on the effect of magnetic fields on nucleii. Hydrogen nucleii are especially sensitive to magnetic fields. So nuclear magnetic resonance is particular easy to demonstrate on water. By easy, I mean with very expensive and complex radio frequency devices.
    Nuclear magnetic resonance is particularly useful in magnetic resonance imaging (MRI). MRI devices are in any hospital.
    While the water molecules don't interact very strongly with a static magnetic field outside of radio frequency effects, you can place things in water which do interact strongly with static magnetic fields. Some work has been done on these things, but I don't think the field is saturated just yet. There is a tradeoff here between the complexity of the experiment and the complexity of the theory.
    Iron filings can be mixed with water to form complex mixtures that do interact with a magnetic field. I am sure there are simple experiments one can do with slurries of water and iron filings. The theory of such phenomena would not be easy, but the experiments sure would be. It wouldn't be the direct interaction of water with magnetic fields, but water would greatly effect the dynamics of such a slurry. You could suspend iron filings in a sol gel, maybe even in Jello. That could be interesting. Interpreting the results could be a bear.
    Then there is the field of magnetohydrodynamics. Scientists and engineers have done a lot of research on how magnetic fields affect moving electrolyte solutions. An electrolyte solution also could interact with the magnetic field via the electrolyte. You could pour water through a magnetic field and measure the voltage across it. Or you could run a current through a salt solution and look at the changes in motion due to a magnetic field,
    There are probably some experiments of medium difficulty one can do with magnetohydrodynamics. The theory of electrolytes in water is probably worked out better than the theory of iron filings in water.
    Sharks are sometimes said to sense static magnetic fields. They navigate partly using the earth's magnetic field. However, they can't sense the static magnetic field directly. They sense the electric currents generated by salt water moving in the earth's magnetic field. Their bodies have sensors for electric currents, not magnetic fields. The magnetic fields induce electric currents. If you have a pet shark, then you may try seeing how a magnetic affects him.
    There are bacteria that use magnetic fields to orient their motion. They live in muddy water. These bacteria are quite harmless. They contain magnetite nanoparticles that help them orient. Maybe you could try to culture them and water, and do some experiments. I don't know how difficult it would be to grow them. I wonder how a suspension of these bacteria would respond to a horseshoe magnet. There may be effects that could be seen without a microscope.
    Electric currents can be generated in salt water by the Hall effect. Experiments measuring the Hall effect in salt water have a nice biology connection via the sharks. However, the Hall effect in salt water is not because of any direct effect of magnetic fields on water molecules.
    To summarize: I think that you could make an interesting project with water if you place something in the water that interacts with a static magnetic field. Iron, salt, sharks, ...
    Last edited: Jun 15, 2012
  4. Jun 17, 2012 #3
    Thank you so much for the detailed reply.

    I will be investigating many of the suggestions above in progressing with the project.
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