On the internet i found decent treatments only in German courses.There are some courses on QM in English too,just google:"Clebsch-Gordan coefficients/theorem".The only complete and at the same time comprehendable & nonmathematized version you can find in the old book of Cohen-Tannoudji.A bit more rigurous is the description in Sakurai's "Modern Quantum Mechanics" and a rigurous treatment can be given in the context of group theory and representations.Wigner's book or any other book entitled "Group Theory in/and Quantum Mechanics" will be good enough.Personally I've been taught the intuitive approach by Cohen-Tannoudji.Angular momentum is a physical quantity that describes the rotational motion of an object or system. It is the product of an object's moment of inertia and its angular velocity.
The formula for calculating angular momentum is L = Iω, where L is angular momentum, I is moment of inertia, and ω is angular velocity. Angular momentum is measured in units of kg*m^2/s.
According to the law of conservation of angular momentum, the total angular momentum of a system remains constant in the absence of external torques. In other words, if no external forces act on a system, the total angular momentum will remain constant.
Linear momentum is a measure of an object's linear motion, while angular momentum is a measure of an object's rotational motion. Linear momentum is calculated by multiplying an object's mass by its velocity, while angular momentum is calculated by multiplying an object's moment of inertia by its angular velocity.
In a closed system, the total angular momentum remains constant, but individual objects within the system can transfer angular momentum to each other. This process is known as the addition of angular momentum. It follows the principle of conservation of angular momentum, where the total angular momentum before a collision or interaction is equal to the total angular momentum after the collision or interaction.