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

Explanation

Using the relation, `H=B_(e) cos theta,` we get the magnitude of B given by
`" " B_(e)=(H)/(cos theta)=(0.16)/(cos60^(@))=(0.16)/((1)/(2))`
`" " =0.16xx2=0.32G`
`or" " =0.32xx10^(-4)T " " [therefore 1G=10^(-4)T]`
Direction of B: The earth's field lies in a vertical plane `12^(@)` west of geographic meridian at an angle of `60^(@)` above the horizontal line.