A superconducting magnet produces a field at a sample whose temperature can be set…

PHYSICS · Multi-part · Fermi University Physics · Electricity, Magnetism & Electromagnetism · Magnetostatics · Magnetostatics

The Boundary-Value Problem, Ch The magnetic multipole expansion and the magnetic scalar potential

Problem

A superconducting magnet produces a field B=20 TB = 20\,\mathrm{T} at a sample whose temperature can be set anywhere from a few kelvin to room temperature. Take the electron's moment to be the Bohr magneton, μB=9.274×10−24 J T−1\mu_B = 9.274\times10^{-24}\,\mathrm{J\,T^{-1}}. ((a)) Find the temperature at which the magnetic energy scale μBB\mu_B B equals the thermal energy kBTk_BT. ((b)) Find the ratio μBB/kBT\mu_B B/k_BT with the sample at 300 K300\,\mathrm{K}, and say whether the field strongly aligns electron moments there.

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