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Few Magnetism questions.

  1. Jul 28, 2010 #1
    Some magnetism and Electricity questions. Remember, I am only 13, so don't answer me like your are talking to a Major in Physics, but please answer me with detail, as if you were talking to some one in high school, I want to understand the details of things, not the general idea.


    Question 1. Why can't wood be magnetized, is it because its' Atoms are in such a mess that their magnetic fields will never align?

    Question 2. I understand that a discharge in electricity is caused by a difference in charges ( Am I correct?), but how exactly does the electricity discharge, and how does the charge difference have to do with anything.
     
  2. jcsd
  3. Jul 29, 2010 #2
    1) If you are 13 then trust me and don't bother to understand permanent magnets and magnetism in materials.

    2) Not correct. Discharge has to do with the electric field in a medium (air, for you). Its called dialectic breakdown and it happens because the potential is too large for the insulator to hold, and ultimately the air becomes ionized and conducts electricity. You need something on the order of about 30,000 volts to jump a centimeter iirc
     
  4. Jul 29, 2010 #3

    DrDu

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    dialectic breakdown, that happens to me regularly, too!
    Probably you meant dielectric breakdown.
     
  5. Jul 29, 2010 #4
    For a material to be magnetized you must have the individual atoms be little magnets, and you must also have the atoms line up their north-south orientations the same way so their combined effects will all add up. A few elements such as iron, nickel and cobalt are good at providing both of those necessary conditions. In wood, only a few of the atoms are little magnets, and even those atoms which are little magnets can't be made to point their north and south in the same orientation to combine their effects.
     
  6. Jul 29, 2010 #5
    What kind if discharge were you thinking of? When you walk on a carpet and then you touch something metal you might feel a small shock. The friction of walking scrapes some electrons off of the surfaces. Then if you have two different materials involved, one material has more of an "affinity" for those free electrons than the other does. The material where more than average electrons gather is a negative pole, and the material where less than average electrons gather is a positive pole. When you touch something metal like the kitchen faucet, some charges may be transported to or from the metal.

    The electronic circuit component called a capacitor, which is a pair of metal plates that are parallel to each other and close together, uses this same principle (charge separation) to form an excess of electrons on one plate and a deficiency of electrons on the other plate. When the two wires of the capacitor are connected through some other path, the capacitor will discharge through the external path, which means ending the charge separation, restoring more atoms to their neutral state.
     
  7. Jul 29, 2010 #6

    Delta2

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    Q1. Wood is composed of many different molecules which in turn are composed of many atoms of different elements. It mostly contains atoms of the element Carbon. Carbon just doesnt behave the same as Iron in the presence of external magnetic field. The detailed why needs Quantum Physics in order to be presented accurately.

    Q2. A discharge is caused between two points that have sufficiently large potential difference. Potential difference is caused by a proper distribution of charges in the space. We can say that a difference in charges(=having many positive charges in one point and many negative charges in another nearby point) can cause a potential difference.

    The mechanism of electric discharge in simple words is that the charges that were used to create the potential difference together with the charges of the surrounding medium(if there are no charges in the medium i.e air they can be created with what is called dielectric breakdown process as mentioned in a previous post) will move under the influence of the electric force (i guess u already know that between electric charges there is a force which might be repuslive or attractive) and this movement of charges can create light which is the main thing we observe when an electric discharge happens.

    The difference in charges(more accurately speaking a proper distribution of charges) creates a potential difference which in turns creates an electric field which exerts an electric force on the charges.

    Although the notion of potential and potential difference is abit advanced for your age, nowdays potential is considered more fundamental notion than the electric field and the electric force.
     
  8. Jul 29, 2010 #7
    Q1 -Are you talking about or Paramagnetism or Diamagnetism ,
    Almost everything is magnetic to some degree ,
    if the wood was wet , you could probably hang that piece of wood on a torsion setup ,
    and have it nicely balanced , you could probably push that piece of wood around with a strong bar magnet , as water is fairly diamagnetic i have done this with bags of water .
    And there is also Corona discharge
     
    Last edited: Jul 29, 2010
  9. Aug 31, 2010 #8
    can you any one explain what is the exact definition of asperomagnetism and superparamagnetism?
     
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