Suppose that the magnetic dipole moment of Earth is 9.6 x 1023 J/T. (a) If the origin of this magnetism were a magnetized iron sphere at the center of Earth, what would be its radius? (b) What fraction of the volume of Earth would such a sphere occupy? The radius of Earth is 6.37 x 106 m. Assume complete alignment of the dipoles. The density of Earth's inner core is 11 g/cm³. The magnetic dipole moment of an iron atom is 2.1 × 1023 J/T. Iron has a molar mass of 55.9 g/mol. (Note: Earth's inner core is in fact thought to be in both liquid and solid forms and partly iron, but a permanent magnet as the source of Earth's magnetism has been ruled out by several considerations. For one, the temperature is certainly above the Curie point.) (a) Number i Units (b) Number i Units

Suppose that the magnetic dipole moment of Earth is 9.6 x 1023 J/T. (a) If the origin of this magnetism were a magnetized iron sphere at the center of Earth, what would be its radius? (b) What fraction of the volume of Earth would such a sphere occupy? The radius of Earth is 6.37 x 106 m. Assume complete alignment of the dipoles. The density of Earth's inner core is 11 g/cm³. The magnetic dipole moment of an iron atom is 2.1 × 1023 J/T. Iron has a molar mass of 55.9 g/mol. (Note: Earth's inner core is in fact thought to be in both liquid and solid forms and partly iron, but a permanent magnet as the source of Earth's magnetism has been ruled out by several considerations. For one, the temperature is certainly above the Curie point.) (a) Number i Units (b) Number i Units