Charge density many of them in a macroscopic volume (there are about 10 conduction electrons in a cubic centimeter of copper) the continuous approximation is very accurate when applied to macroscopic volumes, and even microscopic volumes above the nanometer level. At atomic scales, due to the uncertainty principle of quantum mechanics, a charged particle does not "have" a precise position but is represented by a probability distribution, so the charge of an individual particle is not concentrated at a point but is 'smeared out' in space and acts like a true continuous charge distribution. This is the meaning of 'charge distribution' and
Particle-beam weapon Particle-beam weapon A particle-beam weapon uses a high-energy beam of atomic or subatomic particles to damage the target by disrupting its atomic and/or molecular structure. A particle-beam weapon is a type of directed-energy weapon, which directs energy in a particular and focused direction using particles with miniscule mass. Some particle-beam weapons have potential practical applications, e.g. as an antiballistic missile defense system for the United States and its cancelled Strategic Defense Initiative. The vast majority, however, are science fiction and are among the most common weapon types of the genre. They have been known by myriad names: phasers, particle accelerator