In electromagnetism, charge density is a measure of electric charge per unit volume of space, in one, two or three dimensions. More specifically: the linear, surface, or volume charge density is the amount of electric charge per unit length, surface area, or volume, respectively. The respective SI units are C·m−1, C·m−2 or C·m−3.
Like any density, charge density can depend on position, but because charge can be negative - so can the density. It should not be confused with the charge carrier density, the number of charge carriers (e.g. electrons, ions) in a material per unit volume, not including the actual charge on the carriers.
In chemistry, it can refer to the charge distribution over the volume of a particle; such as a molecule, atom or ion. Therefore, a lithium cation will carry a higher charge density than a sodium cation due to the lithium cation's having a smaller ionic radius, even though sodium has more electrons (11) than lithium (3).
Read more about Charge Density: Free, Bound and Total Charge, Homogeneous Charge Density, Discrete Charges, Relative Charge Density, Charge Density (quantum Mechanics), Application
Famous quotes containing the word charge:
“I never thought that the possession of money would make me feel rich: it often does seem to have an opposite effect. But then, I have never had the opportunity of knowing, by experience, how it does make one feel. It is something to have been spared the responsibility of taking charge of the Lord’s silver and gold.”
—Lucy Larcom (1824–1893)