A compass needle free to turn in a horizontal plane is placed at the center of circulaum coil of $30$ turns and radius $12\;cm$ . The coil is in a vertical plane making an angle of $45^{\circ}$ with the magnetic medician. when the current in the coil is $0.35\;A$ the needle points west to East. Determine the horizontal component of the earth's magnetic field at the location .

Question

$\begin{array}{1 1} 3.9 \times 10^{-4}\;T \\ 3.9 \times 10^{4}\;T \\ 3.9 \times 10^{-5} \;T \\ 3.9 \times 10^5 \end{array} $