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

Homework Help: Magnetic Fields

  1. Mar 14, 2010 #1
    1. The problem statement, all variables and given/known data

    Two current carrying wires cross at right angles (like a + sign).

    Wire 1 has current directed horizontally to the left. Wire 2 has current directed vertically up.

    If the wires are not restrained, what statement best describes the motion of the wires?

    A) Wire 1 moves out of the page; Wire 2 moves into the page
    B) Wire 1 rotates clockwise; Wire 2 rotates counterclockwise
    C) Wire 1 rotates counterclockwise; Wire 2 rotates clockwise
    D) Wire 1 moves up; Wire 2 moves to the left
    E) Wire 1 moves down; Wire 2 moves to the right

    3. The attempt at a solution

    The wires will rotate until the magnetic fields are in the same direction. Therefore I think Wire 1 will move up and Wire 2 moves to the left.

    Have I visualized it correctly?
     
  2. jcsd
  3. Mar 14, 2010 #2

    tiny-tim

    User Avatar
    Science Advisor
    Homework Helper

    Hi 05holtel! :smile:

    I think you're misunderstanding the terminology …

    if wire 1 moves up and wire 2 moves to the left, then they're moving parallel to themselves, and the field directions won't change.
     
  4. Mar 14, 2010 #3
    Oh Yeah,oops

    Rotating Wire 1 clockwise and Wire 2 counterclockwise would make the magnetic fields go in the same direction. Correct?
     
  5. Mar 14, 2010 #4

    tiny-tim

    User Avatar
    Science Advisor
    Homework Helper

    come on … you're just guessing aren't you? :wink:

    Rotating Wire 2 clockwise and Wire 1 counterclockwise would also make the magnetic fields go in the same direction, wouldn't it?

    So which one is correct, and why? :smile:
     
  6. Mar 15, 2010 #5
    I am really confused still,

    I know I have to draw first the magnetic field that Wire 1 makes at the points shown on Wire 2. Use those magnetic fields and the current of Wire 2 to find the forces on Wire 2. Repeat the same procedure for the magnetic field that Wire 2 makes at the points shown on Wire 1. Use this now to find the forces on Wire 2.

    I am not getting any of the suggested solutions
     
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook