185. In the figure, two long parallel wires carry electric currents of equal magnitude in opposite directions through point I. The magnetic field at point M, equidistant from the two wires, is: [Figure: Two parallel wires separated by distance $2d$, point M is at distance $d$ from each wire and distance $a$ below the midpoint] $$\frac{2\mu_0 Id}{\pi(2a^2+d^2)} \quad (1) \qquad \frac{\mu_0 Id}{\pi(2a^2+d^2)} \quad (2)$$ $$\frac{\mu_0 Ia}{\pi(4d^2+a^2)} \quad (3) \qquad \frac{2\mu_0 Ia}{\pi(4d^2+a^2)} \quad (4)$$
\textbf{185.} In the figure, two long parallel wires carry electric currents of equal magnitude in opposite directions through point I. The magnetic field at point M, equidistant from the two wires, is:
\textit{[Figure: Two parallel wires separated by distance $2d$, point M is at distance $d$ from each wire and distance $a$ below the midpoint]}
$$\frac{2\mu_0 Id}{\pi(2a^2+d^2)} \quad (1) \qquad \frac{\mu_0 Id}{\pi(2a^2+d^2)} \quad (2)$$
$$\frac{\mu_0 Ia}{\pi(4d^2+a^2)} \quad (3) \qquad \frac{2\mu_0 Ia}{\pi(4d^2+a^2)} \quad (4)$$