At point A on the earth's surface, the angle of dip is, $\delta=+25^\circ$. At a point B on the earth's surfac

Question

At point A on the earth's surface, the angle of dip is, $\delta=+25^\circ$. At a point B on the earth's surface, the angle of dip is, $\delta=-25^\circ$. We can interpret that:

Accepted Answer

1. **Definition:** The angle of dip (or magnetic inclination, $\delta$) is the angle that the total magnetic field vector of the Earth makes with the horizontal direction at any point on the surface.
2. **Field Direction:** The Earth's magnetic field lines emerge from the magnetic South Pole (near the geographic South) and enter the magnetic North Pole (near the geographic North). Thus, the field lines point roughly from South to North .
3. **Sign Convention:**
   - In the **Northern Hemisphere**, the magnetic field lines point downwards towards the Earth's surface. A dip needle's north pole dips down. By convention, the angle of dip is considered **positive** ($0 < \delta \le 90^\circ$).
   - In the **Southern Hemisphere**, the magnetic field lines point upwards away from the Earth's surface. A dip needle's north pole points up. By convention, the angle of dip is considered **negative** ($-90^\circ \le \delta < 0$).
4. **Analysis:**
   - Point A has $\delta = +25^\circ$, which implies it is in the Northern Hemisphere.
   - Point B has $\delta = -25^\circ$, which implies it is in the Southern Hemisphere.

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