Final answer:
The angular momentum of an object is conserved when the net external torque on the system is zero, adhering to the law of conservation of angular momentum.
Step-by-step explanation:
The angular momentum of an object is conserved in situations where the net external torque acting on the system is zero. When no external torques act on a system, the initial angular momentum will equal the final angular momentum, symbolically expressed as L = L', where L is the initial angular momentum and L' is the final angular momentum. This principle is known as the law of conservation of angular momentum, which is analogous to the conservation of linear momentum where the conservation occurs in the absence of an external force.
Note that while angular momentum is conserved, the individual angular momenta within the system can change, as long as the total angular momentum remains unchanged. This is crucial during events such as collisions, where angular momentum may be transferred between objects, yet the overall system retains the same total angular momentum.