At a certain place,the horizontal component of the Earth's magnetic field is $B_0$ and the angle of dip is $45^o$. The total intensity of the Earth's magnetic field at that place will be:

The angle of dip is the angle

Explain magnetic declination.

The intensity of the magnetic field due to the Earth at a point inside a hollow steel box is:

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

At the magnetic north pole of the earth, the value of the horizontal component of the earth's magnetic field and the angle of dip are, respectively: