Answer: Geographic and magnetic meridians.
- A Geographic and magnetic meridians
- B The field and the horizontal plane
- C The Earth's two magnetic poles
- D The field and the vertical plane
Correct answer: A. Geographic and magnetic meridians
Explanation: Declination is the angle between the geographic meridian and the magnetic meridian (the vertical plane containing the compass needle).
Magnetic field of a bar magnet: field lines emerge from the north pole and re-enter at the south pole outside the magnet, forming continuous closed loops. Image: Geek3, CC BY-SA 3.0, via Wikimedia Commons.
Concept context
Bar magnets, Earth's magnetism, and how different materials respond to an external magnetic field - diamagnetic, paramagnetic, and ferromagnetic behaviour.