splamorprecession.ppt (Slide 5)

• The Correspondence Principle is similar to Ehrenfest's Theorem. The Correspondence Principle states that expectation values satisfy classical equations of motion.
• So, thinking classically, particles exposed to a magnetic field experience a torque. We could apply the Correspondence Principle to the general spin operator to find the expectation value of the torque applied to the particle.
• Point out to the class that the change in the intrinsic angular momentum is perpendicular to the intrinsic angular momentum itself.