At a certain location in Africa, a compass points `12^@` 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^@` above the horizontal. The horizontal component of the earth's held is measured to be 0.16 G. Specify the direction and magnitude of the earth's field at the location.

Explanation

Here, dip angle of a given place on the surface of Earth is `phi = 60^(@)`. Hence, horizontal component of Earth.s magnetic field at this place will be,
`B_(h) = B cos phi`
`therefore B= (B_(h) ) /( cos phi)`
`therefore B= (0.16) /( cos 60^(@))`
`therefore B= (0.16)/( 0.5)`
`therefore B= 0.32 G` (Gauss)
Direction of above magnetic field is in the magnetic meridian (which is a vertical plane, 12° north-west from geographic meridian) from south to north pole of a magnetic needle in the dip circle. (Which shows dip angle 60°). In figure (2) this direction is from S to N along the magnetic axis of magnetic needle in the magnetic meridian.