The north pole of the earth's magnet is near the geographical

Let $m$ and $r$ be the dipole moment and radius of the Earth, respectively. Then, the Earth's magnetic field at the equator is

At which place does the Earth's magnetism become horizontal?

$A$ magnetic needle free to rotate in a vertical plane parallel to the magnetic meridian has its north tip pointing down at $30^{\circ}$ with the horizontal. The horizontal component of the earth's magnetic field at the place is $0.3 \ G$. Then the magnitude of the earth's magnetic field at the location is

Name the elements of the earth's magnetic field.

The ratio between the total intensity of the magnetic field at the equator to the poles is: