At a certain location in Africa, a compass points $12^o$ West of the geographic North. The North tip of the magnetic needle of a dip circle placed in the plane of magnetic meridian points $60^o$ above the horizontal. The horizontal component of the earth's field is measured to be $0.16\, G$. The magnitude of the earth's field at the location will be
$0.23\times10^{-4}\, T$
$0.18\times10^{-4}\, T$
$0.32\times10^{-4}\, T$
$0.81\times10^{-4}\, T$
The line on the earth's surface joining the points where the field is horizontal is
The earth's magnetic field lines resemble that of a dipole at the centre of the earth. If the magnetic moment of this dipole is close to $8 \times 10^{22}\, Am^2$, the value of earth 's magnetic field near the equator is close to....$Gauss$ (radius of the earth $= 6.4 \times 10^6\, m$)
Fill in the blank.
$(i)$ The declination is ...... at higher latitudes.
$(ii)$ The declination in India is ...... .
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
The value of horizontal component of earth's magnetic field at a place is $0.35 \times 10^{-4} \,T$. If the angle of dip is $60^{\circ}$, the value of vertical component of earth's magnetic field is nearly ............. $\times 10^{-4} \,T$