Question

The equation of line on which magnetic field is zero due to system of two perpendicular infinitely long current carrying straight wires, is

• A. $x=y$
• B. $x=2y$
• C. $x=3y$
• D. $3x=y$

Answer 1

The correct option is C $x=3y$

The magnetic field due to each wire would be in opposite directions in the first and third quadrant. Hence the field can be zero only in these quadrants.

Now consider a point (x,y) where the field is zero.

Hence $\frac{{\mu }_{0}I}{2\pi y}-\frac{{\mu }_0\left(3I\right)}{2\pi x}=0$

$⟹x=3y$.