AP Physics B: Electrostatics Formulas

Study Notes

Force Between Charges

Force (F) is computed using F = (k * Q₁ * Q₂) / (r²)
k = 9 * 10⁹ N·m²/C², known as Coulomb's law constant
Q₁ and Q₂ represent the magnitudes of two point charges
r denotes the distance separating the two charges
Force is measured in Newtons (N)

Electric Field Formation

Electric field (E) is determined by E = F / q
F represents the force acting on a charge q, where q = 1.6 * 10⁻¹⁹ C (elementary charge)
E is expressed in Newtons per Coulomb (N/C)

Electric Field from Point Charge

Electric field can also be calculated with E = (k * Q) / r²
Q indicates the point charge, while r is the distance to the charge
Units for electric field are Newtons per Coulomb (N/C)

Work Done on Charges

Work (W) required to move a test charge is given by W = q * E * d
Variables are defined as q = test charge, E = electric field, and d = distance moved
Work is measured in Joules (J)

Energy Relationships

Relationship: W = KE = PE where
- W = work done
- KE = kinetic energy
- PE = potential energy
All terms are expressed in Joules (J)

Voltage Calculations

Voltage (V) can be calculated using V = PE / q
- Also represented as V = (q * E * d) / q, simplifying to V = W / q
Voltage units are volts, defined as Joules per Coulomb (V, J/C)

Voltage and Electric Field

Voltage connects with electric fields as V = Ed
Here, E is the electric field strength and d is the distance, measured in volts (V, J/C)

Work and Voltage

Work can also be expressed as W = q * V
Where q is the test charge and V is voltage, expressed in Joules (J)

Electric Field from Voltage

Electric field can be derived from voltage using E = V / d
This formula gives electric field strength in volts per meter (V/m)

Voltage from Point Charge

Voltage from a single charge is calculated as V = (k * Q) / r
Units remain consistent in volts (V, J/C)

Voltage and Permittivity

Voltage in relation to permittivity is expressed as V = Q / (4 * π * ∈₀ * r)
∈₀ is the permittivity of free space, shaping electrical interactions

Capacitance

Capacitance (C) is defined by the formula C = Q / V
Where Q is the charge and V is the voltage; measured in Farads (F)

Capacitance of Plate Capacitors

Plate capacitance can be deduced using C = (A * K) / (4 * π * k * d)
- A = area, K = dielectric constant, k = coulomb's law constant, d = distance
Another formula for plate capacitors: C = (∈₀ * A * K) / d

Energy Stored in Capacitors

Energy (E) stored in a capacitor is calculated as E = ½ * C * V²
- C = capacitance, V = voltage
Alternatively, energy can be assessed using E = ½ * Q * V

Permittivity of Free Space

Permittivity of free space is defined as ∈₀ = 1 / (4 * π * k)
Relates the spatial capabilities of charges to produce electric fields

Coulomb's Law Constant

Coulomb's law constant k is determined by k = 1 / (4 * π * ∈₀)
It sets the strength of electric forces related to unit charge distances

Description

Explore essential formulas related to electrostatics in AP Physics B. This quiz covers key equations and their definitions, including Coulomb's law and electric field calculations. Perfect for students preparing for exams or anyone interested in learning about electric forces.