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Charge carrier density, also known as carrier concentration, denotes the number of charge carriers per volume. In SI units , it is measured in m −3 . As with any density , in principle it can depend on position.
In electromagnetism, charge density is the amount of electric charge per unit length, surface area, or volume. Volume charge density (symbolized by the Greek letter ρ) is the quantity of charge per unit volume, measured in the SI system in coulombs per cubic meter (C⋅m −3), at any point in a volume.
Charge is quantized: it comes in integer multiples of individual small units called the elementary charge, e, about 1.602 × 10 −19 C, [1] which is the smallest charge that can exist freely. Particles called quarks have smaller charges, multiples of 1 / 3 e , but they are found only combined in particles that have a charge that is an ...
The electron density of the ground state of a molecular system contains cusps at the location of the nuclei, and by identifying these from the total electron density of the system, the positions are thus established. From Kato's theorem, one also obtains the nuclear charge of the nuclei, and thus the external potential is fully defined.
The stable nucleus has approximately a constant density and therefore the nuclear radius R can be approximated by the following formula, R = r 0 A 1 / 3 {\displaystyle R=r_{0}A^{1/3}\,} where A = Atomic mass number (the number of protons Z , plus the number of neutrons N ) and r 0 = 1.25 fm = 1.25 × 10 −15 m.
Nuclear density is the density of the nucleus of an atom. For heavy nuclei, it is close to the nuclear saturation density n 0 = 0.15 ± 0.01 {\displaystyle n_{0}=0.15\pm 0.01} nucleons / fm 3 , which minimizes the energy density of an infinite nuclear matter . [ 1 ]
Charge quantization is the principle that the charge of any object is an integer multiple of the elementary charge. Thus, an object's charge can be exactly 0 e, or exactly 1 e, −1 e, 2 e, etc., but not 1 / 2 e, or −3.8 e, etc. (There may be exceptions to this statement, depending on how "object" is defined; see below.)
In atomic physics, the effective nuclear charge of an electron in a multi-electron atom or ion is the number of elementary charges an electron experiences by the nucleus. It is denoted by Z eff . The term "effective" is used because the shielding effect of negatively charged electrons prevent higher energy electrons from experiencing the full ...