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- PHY102 Physics II © Dr.Cem Özdoğan
- The net electric charge of any isolated system is always conserved.
- If two charged particles undergo an annihilation process, they have equal and opposite signs of charge.
- If two charged particles appear as a result of a pair production process, they have equal and opposite signs of charge.
- A photograph of trails of bubbles left in a bubble chamber by an electron and a positron. The pair of particles was produced by a gamma ray that entered the chamber directly from the bottom. Being electrically neutral, the gamma ray did not generate a telltale trail of bubbles along its path, as the electron and positron did.
- Radioactive decay of nuclei, in which a nucleus transforms into (becomes) a different type of nucleus.
- A uranium-238 nucleus (238U) transforms into a thorium- 234 nucleus (234Th) by emitting an alpha particle. An alpha particle has the same makeup as a helium-4 nucleus, it has the symbol 4He. Here the net charge is 238.