AIIMS 2019 Physics Magnetic Field Due to Current MCQ Question

For the resultant magnetic field at point A to be zero due to two parallel current-carrying wires, the magnetic fields produced by each wire must be equal in magnitude and opposite in direction. The magnetic field $B$ due to a long straight wire is given by the formula $B = \frac{\mu_0 I}{2\pi r}$, where $\mu_0$ is the permeability of free space, $I$ is the current, and $r$ is the distance from the wire. If the current $I_1$ in one wire is 3 A (option C), it will produce a magnetic field that perfectly cancels the field from the other wire at point A, resulting in a net magnetic field of zero.

Options A (1 A), B (2 A), and D (4 A) are incorrect because they do not satisfy the condition for equal and opposite magnetic fields at point A, leading to a non-zero resultant magnetic field.