Glossary
Charge (q)
A fundamental property of matter that causes it to experience a force when placed in an electromagnetic field. It can be positive or negative.
Example:
A balloon rubbed against hair gains a static charge, allowing it to stick to a wall.
Coulomb's Law
A fundamental law in electrostatics that quantifies the force between two charged particles, stating it is directly proportional to the product of their charges and inversely proportional to the square of the distance between them.
Example:
Understanding Coulomb's Law allows you to predict how strongly a proton and an electron will attract each other based on their separation.
Coulomb's Law constant (k)
A proportionality constant used in electrostatics that simplifies calculations for electric fields and forces. It is approximately 8.9875 x 10^9 N⋅m²/C².
Example:
When calculating the force between two electrons, you'd use the value of the Coulomb's Law constant (k) to determine the magnitude of their repulsion.
Distance (r)
The separation between the centers of two charged particles, which significantly influences the magnitude of the electrical force between them.
Example:
Doubling the distance between two charged spheres will reduce the electric force between them to one-fourth of its original value.
Electrical force (F)
The attractive or repulsive force that exists between any two charged particles, as described by Coulomb's Law.
Example:
The push you feel when trying to bring two like-charged magnets together is an example of electrical force.
Permeability (μ)
A measure of how easily a material allows a magnetic field to flow through it. Higher permeability indicates that a material can support the formation of a stronger magnetic field.
Example:
Iron has high permeability, making it an excellent core material for electromagnets to concentrate magnetic field lines.
Permittivity (ε)
A measure of how much a material obstructs or resists the formation of an electric field within it. Higher permittivity means weaker electric forces and fields in that material.
Example:
Water has a high permittivity, which is why it's effective at dissolving ionic compounds by weakening the electrostatic attraction between ions.
Permittivity of free space (ε₀)
The electric permittivity of a vacuum, representing the baseline ability of empty space to permit electric fields. It is a fundamental physical constant.
Example:
When calculating the capacitance of a parallel-plate capacitor in a vacuum, you would use the permittivity of free space (ε₀) in the formula.
Relative Permittivity (εr) / Dielectric Constant (κ)
A dimensionless quantity that compares the permittivity of a material to the permittivity of free space, indicating how much better a material is at storing electrical energy compared to a vacuum.
Example:
A capacitor filled with a material having a relative permittivity (κ) of 4 will have four times the capacitance compared to an identical capacitor with a vacuum between its plates.