Equations page banner

Equations Library

Electronics related equations and more.


 Question, comment or suggestion?

Electronics Reference


Coulomb's Law


εo - Permittivity of free space = 8.854x10-12 (C2/Nm2)
εr - Permittivity of materials

When two charged particles are near each other, a force called electrostatic force is exerted on one another. This force may attract the charged particles together or repel the charged particles away from each other, depending on their charged properties. The amount of electrostatic force that exists between two charged particles is described by Coulomb’s Law.

 > Coulomb's Law

Electric Field


An electric field is a vector field consist of distribution vectors, one from each point of the region around a charged object. The magnitude of the electric field at some point near the charged object is defined by the equation above, where F is the electrostatic force acting between the charged object (Qs) and a test charged particle (Q) placed at that point. The direction of the electric field is the same as the direction of the force acting on the test charge.

 > Electric Field

Gauss's Law


E - The electric field component perpendicular or normal to a small element area ΔA
ΔA - The small element area where the field lines pass
- The charge producing the

Gauss’s Law relates the electric field to the charge distribution which has formed this field. It states that the net flux of an electric field (E) through a closed surface is equal to the net charge (Q) enclosed by the surface divided by the permittivity of free space (εo).

 > Gauss's Law

Electric Flux Density


D - The flux density in Coulomb per meter
Ψ - The electric flux in Coulomb
A - The area perpendicular to the flux in m2
εr - Permittivity of materials

Electric flux density is a vector quantity defined as the electric flux per unit area perpendicular to the direction of the electric flux. It has a direction along the electric field lines at the position where the electric flux density is being measured.

 > Electric Flux Density

Electrical Potential Difference

 > Electrical Potential Difference
Make Bread with our CircuitBread Toaster!

Get the latest tools and tutorials, fresh from the toaster.

What are you looking for?