Key Concept of Electrostatic Potential Energy Know for AP Physics C: E&M

Electrostatic Potential Energy (EPE)

The energy stored in a system due to the positions of charged particles.

Coulomb's Constant (ke)

A constant value used in the calculation of electrostatic potential energy, equal to 8.99×10^9 N·m²/C².

Formula for Electrostatic Potential Energy (U)

U = k_e * (q1 * q2) / r, where q1 and q2 are magnitudes of the charges and r is the distance between them.

Attractive Force

When two charges of opposite signs come together, resulting in negative potential energy.

Repulsive Force

When two charges of the same sign come together, resulting in positive potential energy.

Total Electrostatic Potential Energy

The sum of potential energies between all pairs of charges in a system.

Work-Energy Relationship

The work done in moving a charge in an electric field relates to the change in potential energy, W = -ΔU.

Equipotential Surfaces

Surfaces where the electric potential is constant, with no work required to move a charge along them.

Uniform Electric Field

A field where the electric force is constant and parallel, affecting the potential energy of charges within it.

Coulomb’s Law

Describes the force between two charges, stating it is attractive for opposite signs and repulsive for like signs.

Electrostatic Force

The force that exists between charged objects due to their electric charges.

Energy Conservation in Electrostatics

The principle that total energy remains constant in a system where only electrostatic forces act.

Electric Potential (V)

The potential energy per unit charge at a point in space.

Negative Work

Occurs when potential energy decreases as charges come together.

Positive Work

Occurs when potential energy increases as like charges are pushed together.

Potential Energy Change (ΔU)

The difference in electrostatic potential energy when a charge is moved within an electric field.

Charge Distribution

The arrangement of electric charge in a given space, influencing the electrostatic potential energy.

Electric Field Lines

Lines that represent the direction of electric force, always pointing from positive to negative regions.

Sign of Electrostatic Potential Energy (U)

Indicates if the force between two charges is attractive (negative U) or repulsive (positive U).

Work Done in Moving a Charge

Equals the change in potential energy, W = -ΔU.

Capacitance (C)

A measure of a capacitor's ability to store charge per unit voltage.

Voltage (V) in Capacitors

The electric potential difference across a capacitor's terminals.

Energy Stored in a Capacitor

Given by the formula U = (1/2)C*V², indicating how energy storage depends on capacitance and voltage.

Gradient of Potential Energy

Reflects how electric force and potential energy change with distance.

Point Charges

Charged particles that are treated as having no size, used in calculating electrostatic potential energy.

Electric Potential Energy (U) Formula

The overall potential energy in a pair of charges calculated using U = k_e * (q1 * q2) / r.

Kinetic Energy (KE)

The energy of a body in motion, convertible from potential energy in electrostatic systems.

Energy Transfer in Electric Fields

The conversion of potential energy into kinetic energy when charges move in a field.

Surface Charge Density

The amount of electric charge per unit area on a surface, important for capacitors and charge distributions.

Electric Potential Energy in Multiple Charges

Calculated by summing energy contributions from all distinct pairs of charges within the system.

Role of Distance (r)

The separation between two charges, critical for calculating their electrostatic potential energy.

Difference in Electric Potential (ΔV)

The change in voltage between two points in an electric field, influencing charge movement.

Relationship between U and V

U = qV, indicating electrostatic potential energy depends on both the charge and electric potential.

Electric Field Strength (E)

The force per unit charge experienced by a test charge placed in an electric field.

Potential Energy in Electric Fields

Energy associated with the position of charged objects in a field, variable with displacement.

Electric Field Direction

Always from regions of higher potential to lower potential, impacting how charges are influenced.

Electrostatic System

Any configuration of charged particles interacting through electrostatic forces.

Potential Energy vs. Kinetic Energy

The balance of energies in a charge system as it moves through electric fields.

Applications of Capacitors

Used in circuits to store energy based on the principles of electrostatic potential energy.

Equipotential Condition

No work is needed to move a charge within the same equipotential surface.

Energy Considerations in Charges

When like charges move closer, potential energy increases; opposites lower potential energy when they attract.

Electrostatics Overview

The study of electric charges at rest and the forces exerted due to these charges.

Applications of Electrostatic Principles

Fundamental for circuits, devices like capacitors, and understanding molecular interactions.

Electric Potential Energy Dependency

Depends on charge configuration, distances between charges, and external electric fields.