Q.Define the Angle of Dip. What happens to the angle of dip as we move towards the magnetic pole from the magnetic equator?

[!TLDR] The angle of dip $\phi$ is the angle the Earth's resultant field makes with the horizontal at a place; it increases steadily from $0^\circ$ at the magnetic equator to $90^\circ$ at the magnetic poles. [!ANSWER] $\phi$ is the angle …

The angle of dip, or magnetic inclination, $\phi$, at a place is the angle that the Earth's resultant magnetic field $\vec B$ makes with the horizontal there, measured within the vertical magnetic meridian plane. Resolving $\vec B$ into a horizontal component $B_H=B\cos\phi$ and a vertical component $B_V=B\sin\phi$ gives $\tan\phi=\dfrac{B_V}{B_H}$ (Eq. 12.10). Moving from the magnetic equator towards either magnetic pole, the dip increases steadily and monotonically: right at the magnetic equator, the field is purely horizontal ($B_V=0$, $B=B_H$), so $\phi=0^\circ$; right at a magnetic pole, the field is purely vertical ($B_H=0$, $B=B_V$), so $\phi=90^\circ$ (at the magnetic north pole, directed straight up) or the equivalent $270^\circ$ convention at the magnetic south pole (directed straight down). At every i …

Define $\phi$ via $\tan\phi=B_V/B_H$ (Eq. 12.10) and apply the two special cases of section 12.5 (equator: $\phi=0^\circ$; pole: $\phi …

Confusing declination (a horizontal-plane angle between the magnetic and geographic meridians) with the angle of dip (a vertical-plane angle of the resultant field above/below the …