$A$ circular coil of wire consisting of $n$ turns,each of radius $8 \ cm$,carries a current of $0.4 \ A$. The magnitude of the magnetic field at the centre of the coil is $3.14 \times 10^{-4} \ T$. The value of $n$ is (Take $\mu_0 = 12.56 \times 10^{-7} \ T \cdot m/A$)

  • A
    $1$
  • B
    $10$
  • C
    $100$
  • D
    $1000$

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