The direction of the null points is on the equatorial line of a bar magnet,when the north pole of the magnet is pointing

$A$ magnetic compass needle oscillates $30$ times per minute at a place where the angle of dip is $45^{\circ}$,and $40$ times per minute where the angle of dip is $30^{\circ}$. If $B_1$ and $B_2$ are respectively the total magnetic field due to the earth at the two places,then the ratio $B_1/B_2$ is best given by:

Explain the angle of dip.

$A$ compass needle which is allowed to move in a horizontal plane is taken to a geomagnetic pole. It

Due to the earth's magnetic field,charged cosmic ray particles

Define the angle of dip and the angle of declination.