91Ó°ÊÓ

Theenergy difference between parallel and antiparallel alignments of the $z$component of the electron’s spin magnetic moment is, $\mathrm{Δ}U=6.0×{10}^{-25}\text{J}$

The potential energy of the spin magnetic dipole moment kept in an external magnetic field is given by the dot product of the spin magnetic dipole moment and the external magnetic field.The expression for the magnitude of the magnetic field is given as follows,

$B=\frac{\mathrm{Δ}U}{2{\mathrm{μ}}_B}$

Here, $\mathrm{Δ}U$is theenergy difference between parallel and antiparallel alignments, and ${\mathrm{μ}}_B$is themagnetic dipole moment with the value$9.27×{10}^{-24}\mathrm{J}/\mathrm{T}$.

Substitute all the values in the expression for the magnitude of the magnetic field.

$$\begin{gathered} B=\frac{6.0×{10}^{-25}\text{J}}{2×9.27×{10}^{-24}\text{J/T}} \\ =\frac{3×{10}^{-1}}{9.27}\text{T} \\ =0.3236×{10}^{-1}\text{T}×\frac{1000\text{mT}}{1\text{T}} \\ =32.36\text{mT} \end{gathered}$$

Thus, the magnitude of the magnetic field is$32.36\text{mT}$ .