Find the magnetic moment of a diamagnetic helium atom induced by an external magnetic field B. Hint:

Find the magnetic moment of a diamagnetic helium atom
induced by an external magnetic field B. Hint: The diamagnetism of helium is
due to compensation of moments of oppositely directed spins of two electrons in
helium. To explain the origin of diamagnetism in helium atom, that is, the
absence of the total momentum in the absence of an external magnetic field,
classical description assumes that the orbital radii of the two electrons are a
and electrons on the orbit have the same velocities but opposite directions.