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Homework Help: Magnetic field between 2 parallel wires

  1. Nov 29, 2011 #1
    1. The problem statement, all variables and given/known data
    I have 2 infinitely long parallel wires each carrying a charge of 1 amp in the same direction, and I have to find the magnetic field at a specific point in between them, and I know the distance to it from each of them.

    2. Relevant equations
    This is what I'd like to know.

    3. The attempt at a solution
    I've searched through various books, & websites, and I can't find anything about the magnetic field at a point between them. Only at one of the wires. I basically just want to know what equation I have to use.
  2. jcsd
  3. Nov 29, 2011 #2
    What is the formula given for the magnetic field at one of the wires?
  4. Nov 29, 2011 #3

    Where u is a constant, I is the current, and d is the distance between the wires.
  5. Nov 29, 2011 #4
    The equation you have given:

    B = μI/2∏d is the magnetic field strength at a distance d from a SINGLE wire.

    If 2 wires have current flowing in the SAME direction then the magnetic fields between the wires are in OPPOSITE directions...... Can you take it from here ??
  6. Nov 29, 2011 #5
    This is not a formula for the magnetic field "at one of the wires" as you indicated. It is the formula for the magnetic field at a distance d from the wire. This is the formula you need. The point you are interested in is at a distance d1 from one of the wires and at a possibly different distance d2 from the other wire. Calculate the two magnetic fields and then add them together. Remember that the magnetic field is a vector, so you will need to do a vector addition, not simpy add the numbers together. technician has given you a good hint in that regard.
    Last edited: Nov 29, 2011
  7. Nov 29, 2011 #6
    Thank you Jimmy..... I wish that I had used the term 'vector'..... more general than what I said
  8. Nov 30, 2011 #7
    Ah thank you. It appears my physics books, and the internet are conspiring against me.
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