PHYSICS · Multi-part · CBSE · Physics · Electricity: Magnetic and Heating Effects · Electricity: Magnetic and Heating Effects
Problem
The magnetic field of Earth can be modeled, to first approximation, as that of a magnetic dipole whose magnetic South pole lies near the geographic North Pole.
(a) Describe the orientation of a freely pivoted compass needle at Earth’s magnetic equator compared with its orientation at Earth’s magnetic North Pole.
(b) Explain why the magnetic field lines are nearly horizontal at the magnetic equator but nearly vertical at the magnetic poles.
(c) Earth’s dipole axis is tilted about 11∘ relative to Earth’s rotational axis. Discuss how this tilt affects compass readings taken at the same latitude but different longitudes.
(d) A satellite in low-Earth orbit measures the magnitude of Earth’s magnetic field to be appreciably smaller than the value measured at the surface directly below. Using the dipole model, give a qualitative argument for how the field magnitude depends on distance from Earth’s center and why the satellite observes a weaker field.