Magnetics

As shown in the figure, a long straight conductor with semicircular arc of radius \(\frac{\pi}{10}\)m is carrying current \(\mathrm{I=3A}\). The magnitude of the magnetic field, at the center O of the arc is :

(The permeability of the vacuum \(=4\pi\times10^{-7}~\mathrm{NA}^{-2}\))