At the Earth’s equator, the magnetic field is about 4 × 10⁻⁵ T. If the Earth’s radius is 6.4 × 10⁶ m, then its magnetic dipole moment is closest to which order of magnitude?

Question

Accepted Answer

10²³ A m². Equatorial field B = (mu0/4pi) M/r^3, so M = B r^3/(1e-7) = 4e-5 * (6.4e6)^3 / 1e-7 ~ 1.05e23 A m^2, i.e. order 10^23.

At the Earth’s equator, the magnetic field is about 4 × 10⁻⁵ T. If the Earth’s radius is 6.4 × 10⁶ m, then its magnetic dipole moment is closest to which order of magnitude?

Solution

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