The angle between the magnetic meridian and geographical meridian is called

In the magnetic meridian of a certain place,the horizontal component of the earth's magnetic field is $0.26 \ G$ and the dip angle is $60^{\circ}$. What is the magnetic field of the earth at this location (in $G$)?

If $B_V$ and $B_H$ are respectively the vertical and horizontal components of the earth's magnetic field at a place where the angle of dip is $60^{\circ}$, then the total magnetic field at that place is

$A$ small bar magnet $A$ oscillates in a horizontal plane with a period $T$ at a place where the angle of dip is $60^o$. When the same needle is made to oscillate in a vertical plane coinciding with the magnetic meridian,its period will be

What is the dynamo effect?

The plane of a dip circle is set in the geographic meridian and the apparent dip is $\delta_1$. It is then set in a vertical plane perpendicular to the geographic meridian. The apparent dip angle is $\delta_2$. The declination $\theta$ at the place is