# 7: Angular Momentum

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• 6: Angular Momentum
Angular momentum is the rotational analog of linear momentum. It is an important quantity in classical physics because it is a conserved quantity. The extension of this concept to particles in the quantum world is straightforward.
• 7.5: Rigid Rotor
Microwave rotational spectroscopy uses microwave radiation to measure the energies of rotational transitions for molecules in the gas phase. It accomplishes this through the interaction of the electric dipole moment of the molecules with the electromagnetic field of the exciting microwave photon.
• Spherical Harmonics
Spherical Harmonics are a group of functions used in math and the physical sciences to solve problems in disciplines including geometry, partial differential equations, and group theory.

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