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where e is the charge of an electron, ε 0 is the permittivity of free space, ħ is the reduced Planck constant and c is the speed of light. This constant is proportional to the square of the coupling strength of the charge of an electron to the electromagnetic field.
Continuous charge distribution. The volume charge density ρ is the amount of charge per unit volume (cube), surface charge density σ is amount per unit surface area (circle) with outward unit normal n̂, d is the dipole moment between two point charges, the volume density of these is the polarization density P.
p →: Product of an object's mass and velocity kg⋅m/s L M T −1: vector, extensive Pop: p →: Rate of change of crackle per unit time: the sixth time derivative of position m/s 6: L T −6: vector Pressure gradient: Pressure per unit distance pascal/m L −2 M 1 T −2: vector Temperature gradient
Unit name Symbol Base units E energy: joule: J = C⋅V = W⋅s kg⋅m 2 ⋅s −2: Q electric charge: coulomb: C A⋅s I electric current: ampere: A = C/s = W/V A J electric current density: ampere per square metre A/m 2: A⋅m −2: U, ΔV; Δϕ; E, ξ potential difference; voltage; electromotive force: volt: V = J/C kg⋅m 2 ⋅s −3 ⋅A ...
The elementary charge, usually denoted by e, is a fundamental physical constant, defined as the electric charge carried by a single proton (+1 e) or, equivalently, the magnitude of the negative electric charge carried by a single electron, which has charge −1 e.
The coulomb (symbol: C) is the unit of electric charge in the International System of Units (SI). [ 1 ] [ 2 ] It is defined to be equal to the electric charge delivered by a 1 ampere current in 1 second .
The concept of natural units was introduced in 1874, when George Johnstone Stoney, noting that electric charge is quantized, derived units of length, time, and mass, now named Stoney units in his honor. Stoney chose his units so that G, c, and the electron charge e would be numerically equal to 1. [4]
1.068 × 10 −19 C (2/3 e)—Charge of up, charm and top quarks [2] 1.602 × 10 −19 C: The elementary charge e, i.e. the negative charge on a single electron or the positive charge on a single proton [3] 10 −18: atto-(aC) ~ 1.8755 × 10 −18 C: Planck charge [4] [5] 10 −17: 1.473 × 10 −17 C (92 e) – Positive charge on a uranium ...