Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Water and magnet

  1. Jan 19, 2010 #1
    So, i am considering to do experiment on water and magnet for my research paper. So what i am planning to do is, i will drop a strong magnet on the water from a particular height and i will record down the height of the 'jumping' water due to contact with the magnet upon landing on water. So what i want to know is, if i vary the height of the magnet from the water, would the height of the 'jumping' water vary as well? Or is there any possible variable which i can change to get a nice graph? Or even, do you think this is even a doable experiment?

    Comments and recommendations are highly appreciated. THanks
  2. jcsd
  3. Jan 19, 2010 #2


    User Avatar
    Science Advisor
    Gold Member

    Why a magnet? Why do you think a magnet dropped into water will produce a different result than say a rock.
  4. Jan 19, 2010 #3
    i believe that pure H20 would have no reaction from a magnetic field.

    The only possible reaction would be that of MINERALS in the water. Unless the water itself had a very large composition of minerals that could be affected by a magnetic field, you will not see any difference at all.

    Do i think it's a doable experiment ? No. Water as we know it ( consumable by humans ) wouldn't be affected by a magnet in this world. Or at least to a level that you can actually test.
  5. Jan 19, 2010 #4
    Thanks for all the suggestions guys.
    So, i just consulted with my teacher, and i modify my experiment a bit. I will still be using neodymium magnet and drop it down to a tube of water. The water will be added with electrolytes, such as salt or acid, and i will pass electric current through water. So, the water will act as a resistor. So, what i want to measure is, how long does it take for the magnet to fall down to the bottom of the tube filled with water with different values of current/voltage.

    So, what about his new concept?? do you think this experiment is better or what? Comments and suggestions are appreciated. Thanks.
  6. Jan 20, 2010 #5
    Don’t send any current through the water, this will only complicate things.

    Perhaps do this experiment in a slightly different way. Establish first the exact weight and field strength of the magnet and the electrical resistance of a copper pipe. Then drop the magnet in this pipe without any water. Record time taken and work out its speed. This should give you some idea of currents and voltage generated in side the copper. Note that there are 2 opposing currents operating!
    Then insert this copper pipe inside a bigger plastic pipe and fill the space in between the pipes with salty water. The magnet should fall slower and you should be able to calculate its resistivity.

    This way you can do your experiment without having to deal with any of the other properties of water which will only interfere with the results. You could of course also skip the copper pipe experiment and just use 2 plastic pipes with water between them.

    Now find a way to completely stop the magnet from falling without the use of any external equipment. That would make my day!:devil:
  7. Jan 20, 2010 #6
    hey, that's great idea...
    i am going to try that soon
    thanks a lot for the suggestions
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook