AP Physics B: Electrostatics Formulas

E = V / d

E = electric field V = voltage d = distance Units = volts/ meter (v/m)

E = ½ * C * V²

Energy stored in the capacitor. E = energy C = capacitance V = voltage

E = ½ * Q * V

Energy stored in the capacitor. E = energy Q = charge V = voltage

k = 1 / (4 * π * ∈₀)

Equation for finding the coulomb's law constant. k = 9 * 10⁹ - coulomb's law constant ∈₀ = permittivity of free space

∈₀ = 1 / (4 * π * k)

Equation for finding the permittivity of free space. ∈₀ = permittivity of free space k = 9 * 10⁹ - coulomb's law constant

F = (k * Q₁* Q₂) / (r²)

To find the force between two charges with a predefined distance. F = force k = 9 * 10⁹ - coulomb's law constant Q₁ & Q₂ = charges r = distance between the charges Unit = Newtons (N).

E = (k * Q) / r²

To find the magnitude of an electric field from point charge. E = electric field Q = charge r = distance of the charge k = 9 * 10⁹ - coulomb's law constant Unit = Newton / Coulombs (N/C)

E = F / q

To find the magnitude of an electric field. E = electric field F = force q = 1.6 * 10⁻¹⁹ - test charge Unit = Newton ÷ Coulombs (N/C)

V = Ed

V = voltage E = electric field d = distance Units = volts, Jouls / Coulombs (v, J/C)

V = Q / (4 * π * ∈₀ * r)

V = voltage Q = charge ∈₀ = permittivity of free space r = distance Units = volts, Jouls / Coulombs (v, J/C)

V = (k * Q) / r

V = voltage k = 9 * 10⁹ - coulomb's law constant Q = charge r = distance Units = volts, Jouls / Coulombs (v, J/C)

V = PE / q = (q * E * d) / q = w / q

V = voltage q = 1.6 * 10⁻¹⁹ - test charge E = electric field d = distance W = work Units = volts, Jouls / Coulombs (v, J/C)

W = KE = PE

W = work KE = kinetic energy PE = potential energy Units = Jouls (J)

W = q * V

W = work q = 1.6 * 10⁻¹⁹ - test charge V = voltage Units = Jouls (J)

W = q * E * d

Work required to move a test charge a certain charge a certain distance. W = work q = 1.6 * 10⁻¹⁹ - test charge E = electric field d = distance Unit = Jouls (J)

C = Q / V

capacitance of a capacitor C = capacitance Q = charge V = voltage Units = farads, coulombs / volts (F, C/V)

C = (A * K) / (4 * π * k * d)

capacitance of a plate capacitors A = area K = dielectric k = 9 * 10⁹ - coulomb's law constant d = distance

C = (∈₀ * A * K) / d

capacitance of a plate capacitors ∈₀ = permittivity of free space A = area K = dielectric d = distance