Question

Two infinitely long current carrying conductors X and Y are kept parallel to each other, 24 cm apart in vacuum. They carry currents of 5A and 7A respectively, in the same direction, as shown in Figure above. Find the position of a neutral point, i.e. a point where resultant magnetic flux density is zero.
(Ignore earth's magnetic field).

Answer 1

Consider that magnetic field density at point P is zero due to current carrying conductors.
According to right hand palm rule No. 1, direction of magnetic field will be perpendicular to the plane of the paper
(1) Downward due to current flowing in conductor X.
(2) Upward due to current flowing in conductor Y.
Since at point $P,B=0$
$B_1=B_2$
$\frac{{\mu }_0}{2\pi }\frac{L_1}{x}=\frac{{\mu }_0}{2\pi }\frac{L_2}{24-x}$
$\frac{5}{x}=\frac{7}{24-x}$
$5(24-x)=7x$
$5\times 24=12x\Rightarrow x=10cm$ from conductor X.