The magnetic compass is not useful for navigation near the magnetic poles because

Isogonic lines on magnetic map will have

The angle of dip at a place is $40.6°$ and the intensity of the vertical component of the earth's magnetic field $V = 6 \times {10^{ - 5}}$ $Tesla$. The total intensity of the earth's magnetic field $ (I) $ at this place is

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

A short magnetic needle is pivoted in a uniform magnetic field of strength $1 \,T.$  When another magnetic field of strength $\sqrt 3 \,T$ is applied to the needle in a perpendicular direction, the needle deflects through an angle $\theta$, where $\theta$ is....$^o$

The horizontal component of the earth's magnetic field at any place is $0.36 \times 10^{-4} Wb / m ^{2}$. If the angle of dip at that place is $60^{\circ}$, then the value of vertical component of the earth's magnetic field will be ........ $\times 10^{-4}\;W b / m^{2}$