Glossary
Conservation of Energy
A fundamental principle stating that in a closed system, the total amount of energy (including kinetic, potential, and other forms) remains constant, though it can transform from one form to another.
Example:
When a charged particle accelerates in an electric field, its electric potential energy is converted into kinetic energy, demonstrating the Conservation of Energy.
Coulomb's constant (k)
A fundamental physical constant that relates the electric force between charged particles to their charges and the distance between them, used in calculations for electric potential energy and electric force.
Example:
When calculating the electric potential energy between two electrons, you'll use Coulomb's constant to scale the interaction based on their charges and separation.
Distance (between charges)
The spatial separation between two or more charged objects, which inversely affects the electric potential energy between them.
Example:
The closer a proton is to an electron, the smaller the Distance between them, leading to a more negative (and thus stronger attractive) electric potential energy.
Electric Potential
Also known as voltage, it is the electric potential energy per unit charge at a specific point in an electric field, representing the 'push' or 'pull' available to a charge.
Example:
A 9-volt battery provides an Electric Potential difference that can drive current through a circuit, giving each Coulomb of charge 9 Joules of energy.
Electric Potential Energy
The work done by an external force to bring charged particles from infinitely far apart to their current positions, representing stored energy within an electric field.
Example:
When you charge a capacitor, you are storing Electric Potential Energy in the electric field between its plates, ready to be released.
Like charges
Two or more electric charges that have the same sign (both positive or both negative), resulting in a repulsive electric force between them.
Example:
If you try to push two positively charged balloons together, they will repel each other because they are Like charges.
Magnitude (of charges)
The absolute value or size of an electric charge, irrespective of its positive or negative sign.
Example:
A +5 C charge and a -5 C charge both have the same Magnitude of 5 Coulombs, indicating the strength of their electric influence.
Permittivity of free space (ε₀)
A fundamental physical constant representing the ability of a vacuum to permit electric fields, inversely related to Coulomb's constant.
Example:
In advanced electromagnetism, Permittivity of free space is used to describe how electric fields propagate through empty space.
Scalar quantity
A physical quantity that is fully described by its magnitude alone, without needing a direction.
Example:
Temperature is a Scalar quantity; it only has a value (e.g., 25°C) and no direction, just like electric potential energy.
Systems with Multiple Charges
A configuration of three or more point charges where the total electric potential energy is the sum of the potential energies of every unique pair of charges.
Example:
To find the total energy of three charges at the corners of a triangle, you must calculate the potential energy for each of the three unique pairs, forming a System with Multiple Charges.
Unlike charges
Two electric charges that have opposite signs (one positive and one negative), resulting in an attractive electric force between them.
Example:
A positively charged glass rod will attract a negatively charged rubber balloon because they are Unlike charges.
Work
In the context of electric potential energy, it refers to the energy transferred when a force causes a displacement, specifically the energy required to move charges against or with electric forces.
Example:
Lifting a book against gravity requires Work, similar to how moving a positive charge closer to another positive charge requires work against the repulsive electric force.