This preview shows page 1. Sign up to view the full content.
Unformatted text preview: 19. The energy of a magnetic dipole in an external magnetic ﬁeld B is U = −µ · B = −µz B , where µ is
the magnetic dipole moment and µz is its component along the ﬁeld. The energy required to change
the moment direction from parallel to antiparallel is ∆E = ∆U = 2µz B . Since the z component
of the spin magnetic moment of an electron is the Bohr magneton µB , ∆E = 2µB B = 2(9.274 ×
10−24 J/T)(0.200 T) = 3.71 × 10−24 J. The photon wavelength is
(6.63 × 10−34 J · s)(3.00 × 108 m/s)
= 5.36 × 10−2 m .
3.71 × 10−24 J ...
View Full Document