What affects angular momentum?

Hint:Angular momentum of any object can be defined as the rotational momentum or rotational identical of the linear momentum of a body. It is a conserved quantity which means that the total angular momentum of a closed system remains unchanged.

Complete step by step solution:
The angular momentum of a body depends upon the rotational velocity and also on the rotational inertia of the body. When any object starts to change its shape if there is no rotational inertia, then the rotational velocity of the body also begins to change if the object has no external torque present.
Consider a system of planets orbiting around a star with no torque or with zero net value of torque, so the angular momentum in this process remains unchanged. As a planet moves in an elliptical orbit, its speed decreases while it is further away from the star, and increases when it is close to the star.

Note: The conservation of angular momentum describes the angular acceleration of an ice skater. In quantum mechanics, we describe angular momentum in the form of an operator. Also in quantum mechanics, we have a new kind of Angular momentum which is known as spin angular momentum which is caused by the spin of the fundamental particles. That is why in quantum mechanics we have orbital, spin and total angular momentum where orbital angular momentum is due to the orbital motion of electrons. The total angular momentum is defined as the combination of the spin and orbital angular momentum.$ \Rightarrow \overrightarrow J = \overrightarrow L + \overrightarrow S $
Where, $J$ is the total angular momentum, $L$ orbital angular momentum, $S$ spin angular momentum