$\begin{array}{1 1} \large\frac{\mu_0}{4 \pi} .\frac{2I}{R} \text{ acting perpendicular to OA towards right} \\ \large\frac{\mu_0}{4 \pi} .\frac{2I}{R} \text{ acting perpendicular to AO towards right} \\ \large\frac{\mu_0}{4 \pi} .\frac{2I}{R} \text{ acting perpendicular to OA towards left} \\ \large\frac{\mu_0}{4 \pi} .\frac{2I}{R} \text{ acting perpendicular to AO towards left} \end{array} $