Question

At a certain location in Africa, a compass points ${12}^o$ west of the geographic north. The north tip of the magnetic needle of a dip circle placed in the plane of magnetic meridian points ${60}^o$ above the horizontal. The horizontal component of the earth's field is measured to be $0.16G$. Specify the direction and magnitude of the earth's field at the location.

Answer 1

Here declination=${12}^{\circ }$ west.

dip angle =${60}^{\circ }$, $H=0.16gauss=0.16\times {10}^{-4}T$

$H=Rcos\theta$

$⟹R=\frac{H}{cos\theta }=\frac{0.16\times {10}^{-4}}{cos{60}^{\circ }}=0.32\times {10}^{-4}T$

The earth's magnetic field lies in a vertical plane ${12}^{\circ }$ west of geographic meridian at an angle of ${60}^{\circ }$ above the horizontal.