Infinite number of straight wires each carrying current $I$ are equally placed as shown in the figure. Adjacent wires have current in opposite direction. Net magnetic field at point $P$ is

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  • A

    $\frac{{{\mu _0}I}}{{4\pi }}\,\,\frac{{\ln \,2}}{{\sqrt 3 \,a}}\hat k$

  • B

    $\frac{{{\mu _0}I}}{{4\pi }}\,\,\frac{{\ln \,4}}{{\sqrt 3 \,a}}\hat k$

  • C

    $\frac{{{\mu _0}I}}{{4\pi }}\,\,\frac{{\ln \,4}}{{\sqrt 3 \,a}}( - \hat k)$

  • D

    Zero

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  • [AIPMT 2010]

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