The line on the earth's surface joining the points where the magnetic field is horizontal is known as:

Earth's magnetic field always has a horizontal component except at,or the horizontal component of Earth's magnetic field remains zero at:

The relation between $Z_E, H_E$,and $B_E$ is . . . . . . .

The vertical component of the earth's magnetic field is $6 \times 10^{-5} \text{ T}$ at a place where the angle of dip is $37^{\circ}$. The earth's resultant magnetic field at that place will be (Given $\tan 37^{\circ} = \frac{3}{4}$)

$A$ dip needle lies initially in the magnetic meridian when it shows an angle of dip $\theta$ at a place. The dip circle is rotated through an angle $x$ in the horizontal plane and then it shows an angle of dip $\theta'$. Then $\frac{\tan \theta'}{\tan \theta}$ is

Explain geographic meridian and magnetic meridian.