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

If ${\phi_1}$ and ${\phi_2}$ are the angles of dip observed in two vertical planes at right angles to each other and ${\phi}$ is the true angle of dip,then:

$A$ dip circle is adjusted so that its needle moves freely in the magnetic meridian. In this position,the angle of dip is $40^{\circ}$. Now the dip circle is rotated so that the plane in which the needle moves makes an angle of $30^{\circ}$ with the magnetic meridian. In this position,the needle will dip by an angle:

At a point on the surface of the Earth,the value of the horizontal component of the Earth's magnetic field is equal to the value of the vertical component of the Earth's magnetic field. The angle of dip is:

What is magnetic declination?

$A$ dip needle in a plane perpendicular to the magnetic meridian will remain: