Question

Two very thin metallic wires placed along $X-$ and $Y-$axes carry equal currents as shown in figure. $AB$ and $CD$ are lines at ${45}^o$ with the axes. The magnetic fields will be zero on the line

• A. $AB$
• B. $CD$
• C. segment $OB$ only of line $AB$
• D. segment $OC$ only of line $CD$

Answer 1

Answer: (A)

$AB$

All points on AB are equidistant from the two wires. So, magnetic fields are equal and opposite.

Thus, they cancel out.
All points on the wire CD are on either left side or right side of the wires AB and CD.

Hence, magnetic fields will not cancel.