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Magnetic fields

  1. Apr 2, 2010 #1
    The question is this: If we have a magnet within a much larger magnetic field, does it produce the same amount of magnetic field as if it were not in a larger field?

    In other words, if we have a field equation for a magnet ideally, then we have the magnet within a larger field, does the magnet create less magnetic effect?

    This should be simple enough right?
  2. jcsd
  3. Apr 2, 2010 #2
    If I understand your question correctly , you are asking is the smaller magnet still producing its original field even in the presence of the larger field . I would say yes its original field isn't going anywhere . And i would imagine that the B field's energy still would distort space-time the same in its localized area .
  4. Apr 2, 2010 #3
    Thank you. Yes, I was meaning that. However, let me add, will a piece of metal brought near the smaller magnet be attracted as strongly to the magnet as it would have had there not been a larger magnetic field present? Or, will the larger field somewhat mask the smaller magnet's effect, making it have less of an effect on the metal piece than it would out on its own.?
  5. Apr 2, 2010 #4
    I’m not sure , the stronger field might pull the metal towards it , I’m not 100% sure on this one . maybe you could do an experiment.
  6. Apr 2, 2010 #5
    The way it works is that if you have two magnetic fields, essentially they exist out there independently as if the other were not there. This is called the "principle of superposition". Now in a case of practical effects such as measuring the field at various locations or as you suggest measuring the force on magnetic materials, one needs to add up both fields at every point using vector addition to create the sum field. That sum field which is the summation of the two fields will then determine the effects measured. For example if the two fields are equal and opposite at a point they will cancel and a gauss meter will read zero indicating no fields at that point. But if you turn the fields on one at a time the meter will read the plus or minus value of each field at that point.

    In the case of magnetic materials it's a bit complex, but the general rule is that the magnetic material will experience forces in the direction from the weaker part of the field to the stronger. Thus to see what forces it experiences from both fields you have to first add them up to obtain the total field and then with regard to that field the force will be in the direction from the weaker to the stronger part of the field. OK?
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