In Fig. $29-43,$ two long straight wires at separation $d=16.0 \mathrm{cm}$ carry
currents $i_{1}=3.61 \mathrm{m} \mathrm{A}$ and $i_{2}=3.00 i_{1}$
out of the page. (a) Where on the $x$ axis
is the net magnetic field equal to zero?
(b) If the two currents are doubled, is
the zero-field point shifted toward wire
$1,$ shifted toward wire $2,$ or unchanged?