Please wait for the animation to completely load.
The current in the two red wires is 3 A coming out of the page (position is given in meters). The black wire has a current of zero right now, but can have current either into or out of the page depending on the value of the slider. Restart.
Where does the black wire need to be placed (you can drag it around), and what current does it need to have so that the magnetic field will be zero at the origin (0 m, 0 m)?
Develop an expression for the position of the black wire as a function of current so that the magnetic field will be zero at the origin. Verify your expression with the animation.
Problem authored by Anne J. Cox.