Solve this:

Q27. A wire of magnetic moment 'M' is bent to form a circular arc which subtends an angle 90° at the centre then its new magnetic moment is :

             $\left(1\right) \frac{2\mathrm{M}}{\mathrm{\pi }} \left(2\right)\frac{\sqrt{2}\mathrm{M}}{\mathrm{\pi }}$

             (3) $\frac{2\sqrt{2}\mathrm{M}}{\mathrm{\pi }}$                                    (4) $\frac{\mathrm{M}}{\sqrt{2}\mathrm{\pi }}$