# Orbital Angular Momentum

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Related to Orbital Angular Momentum: spin angular momentum

## orbital angular momentum

[′ȯr·bəd·əl ′aŋ·gyə·lər mə′men·təm]## Orbital Angular Momentum

the angular momentum of a microparticle moving in a strong field that has spherical symmetry. The term “orbital angular momentum” is due to the graphic representation of the motion of an atomic electron in a spherically symmetric field of the nucleus in a definite closed orbit.

According to quantum mechanics, the orbital angular momentum *M _{I}* is quantized, that is, its value, as well as its projection on an axis arbitrarily selected in space (z-axis), can assume only certain discrete values:

where *h̷* is Planck’s constant, *l* = 0, 1, 2, …is the azimuthal (orbital) quantum number, and m = *l*, *l* — 1, … , — *l* is the magnetic quantum number. The classification of the states of microparticles according to the values of *l* plays a major role in atomic theory, in the theory of the atomic nucleus, and in collision theory.

M. A. EL’IASHEVICH