Earth's Magnetism And Angle Of Dip

The Earth's magnetic field at a place is described by three elements: declination, the horizontal component $H$, and the angle of dip $\delta$. The dip is the angle the total field makes with the horizontal, related to the components by $\tan \delta =\frac{V}{H}$, where $V$ is the vertical component. Substituting $V=0.3\sqrt{3}\text{G}$ and $H=0.3\text{G}$, we get $\tan \delta =\frac{0.3\sqrt{3}}{0.3}=\sqrt{3}$, so $\delta ={\tan }^{-1}(\sqrt{3})=60^{\circ }$. The option $30^{\circ }$ corresponds to $\tan \delta =\frac{1}{\sqrt{3}}$, which would invert the component ratio. The option $45^{\circ }$ would require equal vertical and horizontal components. The option $90^{\circ }$ would occur only at the magnetic poles, where the horizontal component vanishes. This treatment of the elements of Earth's magnetism follows the NCERT magnetism chapter, where a dip needle and compass measure these quantities. A sanity check confirms that a vertical component larger than the horizontal one gives a dip greater than $45^{\circ }$, consistent with the obtained $60^{\circ }$. These elements vary systematically over the globe, with the dip angle increasing from zero at the magnetic equator to ninety degrees at the magnetic poles, where a freely suspended needle points straight down. Mapping declination, dip, and horizontal intensity is the business of geomagnetism, and navigators historically corrected compass readings for the local declination, underscoring how these abstract field components have very concrete practical consequences for orientation on Earth.