Two long, straight, parallel wires carry currents that are directed perpendicular to the page as shown in the figure. Wire 1 carries a current I1 into the page (in the negative z direction) and passes through the x axis at x = +a. Wire 2 passes through the x axis at x = -2a and carries an unknown current I2. The total magnetic field at the origin due to the current-carrying wires has the magnitude 2 mu0I1/(2pia). The current I2 can have either of two possible values.
(a) Find the value of I2 with the smaller magnitude, stating it in terms of I1 and giving its direction.
(b) Find the other possible value of 12.