Free electrons

Definition

Free electrons are electrons that are not bound to atoms and can move freely within a material. In conductors, these free electrons enable the flow of electric current.

5 Must Know Facts For Your Next Test

1. Free electrons in conductors allow for the establishment of electrostatic equilibrium.
2. In electrostatic equilibrium, the electric field inside a conductor is zero because free electrons redistribute to cancel any internal field.
3. On the surface of a conductor in electrostatic equilibrium, free electrons rearrange themselves so that the electric field just outside is perpendicular to the surface.
4. The density of free electrons affects the conductivity of materials; higher densities usually mean better conductivity.
5. In Gauss's Law applications, free electrons play a critical role in ensuring that the net electric flux through a closed surface is proportional to the enclosed charge.

Review Questions

• What role do free electrons play in achieving electrostatic equilibrium in conductors?
• Why is the electric field inside a conductor zero when it is in electrostatic equilibrium?
• How do free electrons contribute to the validity of Gauss's Law?

Related terms

Electrostatic Equilibrium: A state where all excess charges reside on the surface of a conductor and the electric field within the conductor is zero.

Gauss's Law: A law stating that the net electric flux through any closed surface is equal to $\frac{1}{\epsilon_0}$ times the charge enclosed by that surface.

Conductor: A material that allows for easy flow of electrical charge due to its high density of free electrons.