Fill in the blank.

$(i)$ The declination is ...... at higher latitudes.

$(ii)$ The declination in India is ...... .

A long straight horizontal cable carries a current of $2.5\;A$ in the direction $10^{\circ}$ south of west to $10^{\circ}$ north of east. The magnetic meridian of the place happens to be $10^{\circ}$ west of the geographic meridian. The earth's magnetic field at the location is $0.33\; G ,$ and the angle of $dip$ is zero. Locate the line of neutral points (ignore the thickness of the cable)? (At neutral points, magnetic field due to a current-carrying cable is equal and opposite to the horizontal component of earth's magnetic field.)

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

At a point $A$ on the earth's surface the angle of $\operatorname{dip}, \delta=+25^{\circ} .$ At a point $B$ on the earth's surface the angle of dip, $\delta=-25^{\circ} .$ We can interpret that

A short bar magnet is placed in the magnetic meridian of the earth with north pole pointing north . Neutral points are found at a distance of $30\, cm$ from the magnet on the East - West line, drawn through the middle point of the magnet. The magnetic moment of the magnet in $Am^2$ is close to: (Given $\frac{{{\mu _0}}}{{4\pi }}\, = 10^{- 7}$ in $SI\,units$ and $B_H\, =$ Horizontal component field $= 3.6\times10^{-5}\, tesla$)

At which place, earth's magnetism become horizontal