ε 0 = {\displaystyle \varepsilon _{0}=} 8.85×10−12 F/m = vacuum permittivity.
e = 1.602×10−19C: negative (positive) charge for electrons (protons)
k e = 1 4 π ε 0 = {\displaystyle k_{e}={\tfrac {1}{4\pi \varepsilon _{0}}}=} = 8.99×109 m/F
F → = Q E → {\displaystyle {\vec {F}}=Q{\vec {E}}} where E → = 1 4 π ε 0 ∑ i = 1 N q i r P i 2 r ^ P i {\displaystyle {\vec {E}}={\tfrac {1}{4\pi \varepsilon _{0}}}\sum _{i=1}^{N}{\tfrac {q_{i}}{r_{Pi}^{2}}}{\hat {r}}_{Pi}}
E → = ∫ d q r 2 r ^ {\displaystyle {\vec {E}}=\int {{\tfrac {dq}{{r}^{2}}}{\hat {r}}}} where d q = λ d ℓ = σ d a = ρ d V {\displaystyle dq=\lambda d\ell =\sigma da=\rho dV}
E = σ 2 ε 0 {\displaystyle E={\tfrac {\sigma }{2\varepsilon _{0}}}} = field above an infinite plane of charge.
8.85×10−12 F/m = vacuum permittivity.
= 8.99×109 m/F
where 
where 
= field above an infinite plane of charge.