A hairpin like shape as shown in figure is made by bending a long current carrying wire. What is the magnitude of a magnetic field at point $P$ which lies on the centre of the semicircle ?

• A

  $\frac{{\mu }_{0}I}{4\pi \mathrm{r}}(2-\pi )$
• Correct answer
  B

  $\frac{{\mu }_{0}I}{4\pi \mathrm{r}}(2+\pi )$
• C

  $\frac{{\mu }_{0}I}{2\pi \mathrm{r}}(2+\pi )$
• D

  $\frac{{\mu }_{0}I}{2\pi r}(2-\pi )$

Hence, the correct answer is option: 'B'.