Point particle of point charges cannot be maintained in an equilibrium configuration solely by the electrostatic interaction of the charges. In quantum mechanics, there is a distinction between an elementary particle (also called "point particle") and a composite particle. An elementary particle, such as an electron, quark, or photon, is a particle with no internal structure. Whereas a composite particle, such as a proton or neutron, has an internal structure (see figure). However, neither elementary nor composite particles are spatially localized, because of the Heisenberg uncertainty principle. The particle wavepacket always occupies a nonzero volume. For example, see atomic orbital: The electron
Kelsey (given name) in 1996. It was the 528th most common name for women in the United States in the 1990 census. Kelsey was ranked among the top 100 names for girls born in Scotland in 2007. It was also among the top 100 names for girls born in England and Wales in the late 1990s. People with the given name Kelsey: Kelsey (given name) Kelsey Is a unisex given name of English origin. The name most probably derives from an Old English given name "Ceolsige", which meant "ship's victory", or it could be a place name meaning "Cenel's island". "Cenel's Island" is