Definition
Electrons in the outer shell of an atom that are loosely held and can move easily from one atom to another. The movement of these electrons through a conductor is what constitutes an electric current.
Plain English
Tiny negatively charged particles that aren't tightly attached to any one atom and can drift between atoms. When they move together through a wire, you get electricity.
Context Anchor
Seen in aircraft electrical-system discussions, especially when learning how batteries, alternators, wires, switches, and loads carry current.
Derivation
From Latin liber meaning 'free,' and electron from Greek elektron meaning 'amber.' The Greeks noticed that rubbing amber produced a static charge, so 'electron' became the name for the charged particle. 'Free' here means unattached — not bound to a specific atom.
Why Pilots Care
Free electrons enable current flow in aircraft electrical systems and explain how friction during flight generates static charges that must be dissipated.
Grounding Statement
When an aircraft battery is connected to a complete circuit, free electrons in the wiring begin to move, and electrical equipment can operate.
Intuition Check
Free does not mean extra or unused here. It means able to move through a material rather than being tightly held in one place.
Example Sentence 1
Copper is used in aircraft wiring because it has many free electrons, which makes it an excellent conductor.
Example Sentence 2
Friction with rain and ice can strip electrons from the airframe, leaving free electrons that create a static charge on the surface.