Answer –
Horizontal component of earth’s magnetic field is given by BH = 0.35 G
Angle made by the needle with the horizontal plane is known as the Angle of dip, given by δ=22°
Earth’s magnetic field strength is given by B
We can relate B and BH in following manner –
${{B}_{H}}=B\cos \delta $
Rearranging the above relation, we get –
$B=\frac{{{B}_{H}}}{\cos \delta }=\frac{0.35}{\cos {{22}^{\circ }}}$$$
$B=0.38G$
Hence, 0.38 G is the strength of the earth’s magnetic field at the given location.