Magnetic Forces on Current-Carrying Wires (Conceptual Question)...Is answer correct?

  1. Magnetic Forces on Current-Carrying Wires (Conceptual Question)....Is answer correct?

    Two straight wires are parallel to each other and carry different currents in the same direction. Do they attract or repel each other? How do the magnitudes of these forces on each wire compare?






    The formula used to calculate these attractive or repulsive forces is:



    F = BIL

    F12 = (μ0I1/2πr)I2L2

    F12 = (μ0/2πr) I1I2L2

    F12 = (4π X 10-7/2πr) I1I2L2

    F12 = (2 X 10-7/r) I1I2L2

    F12 represents the force on wire 2 caused by its presence in the magnetic field of wire 1

    I1 is the current flowing in wire 1

    I2 is the current flowing in wire 2

    L2 is the length of the current segment of wire 2 in the field of wire 1

    r is the distance between the wires

    F21 represents the force on wire 1 caused by its presence in the magnetic field of wire 2

    F21 = (μ0I2/2πr)I1L1

    F21 = (μ0/2πr) I1I2L1

    F21 = (4π X 10-7/2πr) I1I2L1

    F21 = (2 X 10-7/r) I1I2L1





    3. Answer

    If two current carrying wires are parallel to each other, their respective magnetic fields either attract or repel each other.



    If two parallel wires have currents traveling in the same direction, the magnetic fields generated by those currents between the wires will both point in opposite directions resulting in the wires attracting each other.

    If two parallel wires have currents traveling in opposite directions, the magnetic fields generated by those currents between the wires will both point in the same direction, in this case, into the plane of the page. These wires would repel each other.



     
    ghadeer likes this.
  2. jcsd
  3. Kurdt

    Kurdt 4,941
    Staff Emeritus
    Science Advisor
    Gold Member

    Thats a very good explanation. So how do the magnitudes compare and do they attract or repel?
     
  4. How do they compare? I'm not sure..
     
  5. Kurdt

    Kurdt 4,941
    Staff Emeritus
    Science Advisor
    Gold Member

    Well you've pretty much worked them out. The magnitude just means the number associated with it and disregarding the direction. What can you say about the two force equations you've derived?
     
  6. Forces are equal (equal magnitude). And parallel currents attract each other.
     
  7. Kurdt

    Kurdt 4,941
    Staff Emeritus
    Science Advisor
    Gold Member

    Very good.
     
Know someone interested in this topic? Share a link to this question via email, Google+, Twitter, or Facebook