At a place,the horizontal and vertical intensities of the Earth's magnetic field are $0.30 \ G$ and $0.173 \ G$ respectively. The angle of dip at this place is.....$^o$

Define geographic meridian and magnetic meridian.

$A$ magnet hung at $45^{\circ}$ with the magnetic meridian makes an angle of $60^{\circ}$ with the horizontal. The actual value of the angle of dip is.

Assume the dipole model for Earth's magnetic field $B$,which is given by:
$B_v = \text{vertical component of magnetic field} = \frac{\mu_0}{4\pi} \frac{2m \cos \theta}{r^3}$
$B_H = \text{horizontal component of magnetic field} = \frac{\mu_0}{4\pi} \frac{m \sin \theta}{r^3}$
where $\theta = 90^\circ - \text{latitude}$ as measured from the magnetic equator.
$(a)$ Find the loci of points for which the dip angle is zero.

At two different places,the angles of dip are respectively $30^{\circ}$ and $45^{\circ}$. At these two places,the ratio of the horizontal component of Earth's magnetic field is:

Consider the plane $S$ formed by the dipole axis and the axis of the Earth. Let $P$ be a point on the magnetic equator and in plane $S$. Let $Q$ be a point of intersection of the geographical and magnetic equators. Obtain the declination and dip angles at $P$ and $Q$.