Two identical copper wires $W1$ and $W2$ placed in parallel as shown in the figure, carry currents $I$ and $2I$, respectively, in opposite directions. If the two wires are separated by a distance of $4r$, then the magnitude of the magnetic field $\overrightarrow{B}$ between the wires at a distance $r$ from $W1$ is
- $\frac{\mu_{0}I}{6\pi r}$
- $\frac{6\mu_{0}I}{5\pi r}$
- $\frac{5\mu_{0}I}{6\pi r}$
- $\frac{\mu_{0}^{2}I^{2}}{2\pi r^{2}}$
