Charge Quantization: $q = ne, \quad e = 1.6 \times 10^{-19}\ \text{C}, \quad [e] = [AT]$

Coulomb's Law: $F = \frac{kq_1 q_2}{r^2}, \quad k = \frac{1}{4\pi\varepsilon_0} = 9 \times 10^9\ \text{N m}^2\text{C}^{-2}, \quad [F] = [MLT^{-2}]$

Permittivity of Free Space: $\varepsilon_0 = 8.85 \times 10^{-12}\ \text{C}^2\text{N}^{-1}\text{m}^{-2}, \quad [\varepsilon_0] = [M^{-1}L^{-3}T^4A^2]$

Electric Field: $E = \frac{F}{q_0} = \frac{kQ}{r^2}, \quad [E] = [MLT^{-3}A^{-1}], \quad \text{unit: N/C}$

Dipole Moment: $p = q \cdot 2l, \quad [p] = [ATL], \quad \text{unit: C·m}$

Dipole Fields (r ≫ l): $E_{\text{axial}} = \frac{2kp}{r^3}, \quad E_{\text{eq}} = \frac{kp}{r^3}, \quad [E] = [MLT^{-3}A^{-1}]$

Ring on Axis: $E = \frac{kQx}{(R^2+x^2)^{3/2}}, \quad E_{\max}\ \text{at}\ x = \frac{R}{\sqrt{2}}$

Gauss's Law: $\Phi = \oint \vec{E} \cdot d\vec{A} = \frac{q_{\text{enc}}}{\varepsilon_0}, \quad [\Phi] = [ML^3T^{-3}A^{-1}], \quad \text{unit: V·m}$

Infinite Wire: $E = \frac{\lambda}{2\pi\varepsilon_0 r}, \quad [\lambda] = [AL^{-1}T], \quad \text{unit: C/m}$

Infinite Plane Sheet: $E = \frac{\sigma}{2\varepsilon_0}, \quad [\sigma] = [AL^{-2}T], \quad \text{unit: C/m}^2$

Electric Potential: $V = \frac{kQ}{r}, \quad E = -\frac{dV}{dr}, \quad [V] = [ML^2T^{-3}A^{-1}], \quad \text{unit: volt (V)}$

Potential Energy: $U = \frac{kq_1 q_2}{r}, \quad [U] = [ML^2T^{-2}], \quad \text{unit: joule (J)}$

Capacitance: $C = \frac{Q}{V} = \frac{\varepsilon_0 A}{d},\quad C_{\text{dielectric}} = \frac{K\varepsilon_0 A}{d}, \quad [C] = [M^{-1}L^{-2}T^4A^2], \quad \text{unit: farad (F)}$

Energy Stored: $U = \frac{1}{2}CV^2 = \frac{Q^2}{2C} = \frac{1}{2}QV, \quad [U] = [ML^2T^{-2}]$