Angle of dip is $90^o$ at
Poles
Equator
Both $(a) $ and $ (b)$
None of these
The vertical component of earth's magnetic field is zero at or The earth's magnetic field always has a vertical component except at the
The horizontal component of the earth's magnetic field is $0.22$ $Gauss$ and total magnetic field is $0.4$ $Gauss$. The angle of dip. is
The magnetic compass is not useful for navigation near the magnetic poles because
A dip circle lies initially in the magnetic meridian, it shows an angle of dip $\delta$ at a place. The dip circle is rotated through an angle $\alpha$ in the horizontal plane and then it shows an angle of dip $\delta^{\prime}$. Hence $\frac{\tan \delta^{\prime}}{\tan \delta}$ is
If magnetic lines of force are drawn by keeping magnet vertical, then number of neutral points will be