In the realm of quantum mechanics, charge conservation remains a fundamental principle that governs the behavior of subatomic particles. It asserts that the total electric charge of an isolated system remains constant over time. This principle plays a crucial role in understanding phenomena such as particle interactions and the creation or annihilation of charged particles.

Example 1: Conservation of Electric Charge

Consider the process of electron-positron annihilation. When an electron collides with its corresponding antiparticle, the positron, they mutually annihilate, resulting in the generation of high-energy photons, such as gamma rays. This phenomenon demonstrates charge conservation since the total charge before annihilation (electron charge + positron charge) is equal to the total charge after annihilation (photon charge).

Example 2: Particle Interactions

Charge conservation also applies to particle interactions. For instance, in the decay of a negative pion (π-), it transforms into a muon (μ-) and a muon neutrino (νμ). The charge of the initial pion (-1) should equal the combined charge of the final products (-1 for muon and 0 for muon neutrino) to obey the law of charge conservation.

Example 3: Creation of Charged Particles

Particle creation processes, such as pair production, illustrate charge conservation. When a gamma ray with sufficient energy interacts with a nucleus, it can produce an electron-positron pair. The total charge before the process (0) is equal to the total charge after the creation of the electron and positron (-1 + 1).

Overall, charge conservation in quantum mechanics provides a fundamental framework for understanding the interplay of charged particles, their interactions, and the conservation of electric charge in various processes.