Give information about the Earth’s magnetic field lines and the location of the magnetic poles.
The magnetic field lines of the Earth resemble that of a magnetic dipole located at the centre of the Earth.
The axis of the dipole does not coincide with the axis of rotation of the Earth but is presently tilted by $11.3^{\circ}$.
The magnetic poles are located where the magnetic field lines due to the dipole enter or leave the Earth.
The location of the north magnetic pole is at a latitude of $79.74^{\circ} \mathrm{N}$ and a longitude of $71.8^{\circ} \mathrm{W}$, a place somewhere in north Canada.
The magnetic south pole is at $79.74^{\circ} \mathrm{S}, 108.22^{\circ} \mathrm{E}$ in the Antarctica.
Isogonic lines on magnetic map will have
The pole near the geographic north pole is called ...... . The pole near the geographic south pole is called ...... .
If $\theta _1$ and $\theta_2$ be the apparent angles of dip observed in two vertical planes at right angles to each other, then the true angle of dip $\theta$ is given by
A magnetic compass needle oscillates $30$ times per minute at a place where the dip is $45^o$, and $40$ times per minute where the dip is $30^o$. If $B_1$ and $B_2$ are respectively the total magnetic field due to the earth at the two places, then the ratio $B_1/B_2$ is best given by
A dip needle in a plane perpendicular to magnetic meridian will remain